Rome at Christmas is the city at its most theatrical. Lights run the length of Via del Corso, the Piazza Navona market fills with sweet stalls and a carousel, and St Peter's Square holds a tree and a nativity scene under the Basilica. The season runs from 8 December 2026 to 6 January 2027, and it rewards planning more than any other time of year. This guide gives you the dates, the closures, the Vatican practicalities and a four-day plan, written for UK travellers. Rome has no German-style market. The nativity scenes, the lights and the Vatican matter more than the stalls.
Rome at Christmas at a glance
Rome at Christmas runs from 8 December 2026, the Feast of the Immaculate Conception, to 6 January 2027, Epiphany. The Piazza Navona market runs longer, from 1 December to 6 January, and St Peter's Square holds its tree and nativity through the whole season. Christmas Day is quiet and mostly closed, so plan around it.
| Date | What happens |
|---|---|
| 28 November 2026 | Christmas World at Villa Borghese opens (best supported date, price still to confirm) |
| 1 December 2026 | Piazza Navona market authorised to open; stalls in recent years opened 6 to 8 December |
| 8 December 2026 | Season starts: Feast of the Immaculate Conception, a public holiday; 100 Presepi opens in St Peter's Square |
| 24 December 2026 | Christmas Eve Mass at St Peter's (time to confirm); museums close early; metro runs until 21:00 |
| 25 December 2026 | Christmas Day: Urbi et Orbi blessing at noon (traditional time, to confirm); most sights closed |
| 27 December 2026 | Free Sunday at the Vatican Museums, 09:00 to 14:00 |
| 1 January 2027 | New Year's Day: Colosseum and Vatican Museums closed |
| 3 January 2027 | First Sunday of the month: free entry to state museums, including the Colosseum |
| 6 January 2027 | Epiphany and the Befana finale in Piazza Navona; Vatican Museums closed |
| 7 January 2027 | 100 Presepi closes |
The best window depends on what you want. Early December brings the lowest hotel prices of the year, short queues and the markets already open. Christmas week, from 23 December to 6 January, is the busiest stretch and also the most atmospheric. The quietest days are 2 to 5 January. Where a date or price is not yet confirmed for 2026, this article says so plainly and tells you where to check.
When is Christmas in Rome?
The Christmas season in Rome starts on 8 December 2026 and ends on 6 January 2027. The lights and markets begin earlier, from late November, and the busiest days run from 23 December to 6 January. Early December brings lower prices and lighter crowds, and 2 to 5 January is the quietest stretch.
The season opens on 8 December, the Feast of the Immaculate Conception, a public holiday in Italy. That is the day the tree and nativity scenes traditionally appear, the 100 Presepi exhibition opens, and Romans start their Christmas shopping. The lights along Via del Corso come on around this time, although the switch-on date is disputed.
Christmas week is the peak. From 23 December to 6 January the centre is crowded, hotel prices jump, and the big sights need booking weeks ahead. The crowds do not thin out properly until 2 January.
For ideas on where else to go before the season starts, see the best places to visit in Europe in November. Direct flights from London take about 2 hours 30 minutes to 2 hours 45 minutes, with British Airways, easyJet, Ryanair, ITA Airways, Wizz Air and Jet2. Most flights land at Fiumicino; Ryanair's Stansted flights use Ciampino. Your passport must have been issued less than 10 years before arrival and be valid for at least 3 months after you leave the Schengen area. A GHIC is free from the NHS and covers medically necessary state healthcare.
Piazza Navona Christmas market: the Festa della Befana
The Piazza Navona Christmas market, the Festa della Befana, is Rome's main Christmas market, authorised to run from 1 December 2026 to 6 January 2027, with free entry. It fills the square with wooden stalls, a carousel, sweet sellers and nativity figures, and it is at its best after dark.
One date needs care. The market is authorised from 1 December, but in recent years the stalls actually opened around 6 to 8 December. Check the opening day before you go, and aim for the second week of December onwards if the market is the main reason for your visit.
Reported hours are 09:00 to 01:00, and 09:00 to 02:00 at weekends, but these are not confirmed by the city for 2026.
What you buy here is different from a German Christmas market: nativity figures, handmade decorations, toys, sweet coal, torrone, roasted chestnuts and panettone. The nativity figures are the heart of it: Romans buy figures for the presepe, the nativity scene they build at home.
The season ends in the square on 6 January 2027, Epiphany, with the arrival of the Befana, the witch who brings sweets to children. The arrival time is not yet confirmed for 2027, and the sources conflict: several 2026 guides give 10:00, while the most recent edition, in 2026, saw the Befana arrive at 14:00. Check the city programme in early January.
Rome's other Christmas markets
Piazza Navona is the main market, but it is not the only one. Rome has smaller authorised markets and Christmas villages, worth knowing about if you are staying more than a few days. The dates below mix authorisation dates and confirmed operating dates.
The most useful smaller market is Piazza Mazzini, in Prati near the Vatican. It runs from 1 December to 6 January with up to 73 cabins, and it is a neighbourhood market, calmer than Navona. Smaller markets also run at Piazza Vittorio Emanuele II, Testaccio and Trastevere through December.
The bigger Christmas villages sit outside the centre. The EUR village, by the EUR Fermi and EUR Palasport metro stations, has a 50-metre Ferris wheel and an ice rink, but its dates are the most confused in Rome: four ranges are in circulation. Christmas World at Villa Borghese is the biggest ticketed Christmas event in the city, with rides, shows and an ice rink. Its best supported dates are 28 November 2026 to 10 January 2027, but the official site showed no dates or prices on 9 November, and the 2026 price is unconfirmed. Christmas Land at the Auditorium runs from 4 December 2026 to 6 January 2027, from 11:00 to 20:00. Cinecitta World, the film-themed park south of the city, runs a Christmas season with entry included in a park ticket, usually about 20 to 30 euros, but its start date is disputed. The Mercato Monti pop-up runs on 12 to 13 and 19 to 22 December 2026, from 10:00 to 20:00.
| Market | Location | Dates | Entry | Notes |
|---|---|---|---|---|
| Piazza Navona, Festa della Befana | Centro Storico | 1 Dec 2026 to 6 Jan 2027 | Free | Main market; stalls often open 6 to 8 Dec in practice |
| Piazza Mazzini | Prati, near the Vatican | 1 Dec 2026 to 6 Jan 2027 | Free | Up to 73 cabins; neighbourhood feel, calmer than Navona |
| Piazza Vittorio Emanuele II | Esquilino | 5 to 26 Dec 2026 | Free | Smaller neighbourhood market |
| Testaccio market | Testaccio | 5 to 26 Dec 2026 | Free | Local market, good for food |
| Trastevere, Largo San Giovanni de Matha | Trastevere | 1 to 30 Dec 2026 | Free | Evening atmosphere, near the food streets |
| Piazza San Cosimato | Trastevere | 21 to 24 Dec 2026 | Free | Four days only |
| EUR Christmas village | EUR, Metro B | Dates conflict: 22 Nov to 6 Jan, 27 Nov to 10 Jan, 1 Dec to 7 Jan, 1 to 26 Dec | Free entry; rides charged | 50-metre Ferris wheel and ice rink; re-check dates |
| Christmas World, Villa Borghese | Villa Borghese | 28 Nov 2026 to 10 Jan 2027 (best supported) | Ticketed; 2026 price unconfirmed | Rides, shows, ice rink; 2025 from 12.50 euros |
| Christmas Land, Auditorium | Auditorium Parco della Musica | 4 Dec 2026 to 6 Jan 2027, 11:00 to 20:00 | Free entry | Concerts nearby in the evening |
| Cinecitta World | South of the city | Start date disputed (7, 8, 9 or 11 Nov) to 6 Jan 2027 | Ticketed, usually about 20 to 30 euros | Film-themed park; check the official site |
| Mercato Monti | Monti | 12 to 13 and 19 to 22 Dec 2026, 10:00 to 20:00 | Free | Vintage and handmade gifts |
St Peter's Square: the tree, the nativity and 100 Presepi
St Peter's Square at Christmas is the single most visited sight of the season, and it is free. The square holds a large Christmas tree, a life-size nativity scene and the 100 Presepi exhibition, all under the Basilica and Bernini's colonnade. Come in the late afternoon, when the lights come on and the square glows.
The 2026 tree, about 25 metres tall, comes from Terranova di Pollino in Basilicata, and the nativity scene comes from Chieti-Vasto in Abruzzo. The inauguration date is not confirmed: no 2026 date had been announced by 9 November. In 2025 the unveiling was on Monday 15 December at 17:00. Do not plan your trip around 12 December, the date one site predicts.
The 100 Presepi exhibition, 100 Nativity Scenes, is the quiet star of the square. It runs from 8 December 2026 to 7 January 2027, per the official 100 Presepi site, which corrects the 6 January closing date given in some guides. The exhibition sits under Bernini's colonnade and shows nativity scenes from around the world, in wood, glass, paper, metal and fabric. Entry is free. Reported hours are 10:00 to 20:00, with an early close at 17:00 on 24 and 31 December, but those hours come from secondary sources only.
The square itself is always open and always free. Security is tight around Christmas: bags are checked, and liquids over 100 ml, glass, flasks, selfie sticks and oversized bags are not allowed through. Dress code applies in the Basilica: cover your shoulders and knees.
Christmas at the Vatican: Mass, Urbi et Orbi and tickets
Christmas at the Vatican is the heart of the season for many visitors, and the part that needs the most planning. The Christmas Eve Mass and the Urbi et Orbi blessing are free, but the Mass needs a ticket requested months in advance, and the 2026 times are not yet confirmed.
Christmas Eve Mass is traditionally held at 22:00 on 24 December, and the Urbi et Orbi blessing is traditionally given at noon on 25 December, both the 2025 pattern. No 2026 Vatican notice had been published by 9 November, and the Christmas liturgy notice is expected in early December.
Tickets for Christmas Eve Mass are free and are requested in advance from the Prefecture of the Papal Household, by email to ordinanze@pontificalisdomus.va or by fax to +39 06 6988 5863. Give your full name, the date, the number of tickets, your postal address and a telephone number. The usual window is October to early November, and tickets are collected in person from the Swiss Guards at the Bronze Doors, one to three days before the Mass. This article is published in late November, so requests for 2026 may already be closed. Never buy tickets from resellers: Mass tickets are always free, and resellers charge thousands of pounds for them.
If you cannot get into the Mass, try the Pantheon's midnight Mass, Santa Maria Maggiore, or English-language services at San Silvestro in Capite and Sant'Isidoro.
The Urbi et Orbi blessing needs no ticket. It is free and open to all in St Peter's Square at noon on Christmas Day, the traditional time. Arrive early: the advice is to clear security by 09:00 to 10:00. Bring warm layers and a waterproof, as you will be standing in the square for hours. The Angelus is also given in St Peter's Square on the Advent Sundays, on 26 December, and on 1 and 6 January. Expect a wider security perimeter on 24 and 25 December, bag checks, and long queues between 17:00 and 19:30 on Christmas Eve. Shoulders and knees must be covered inside the churches.
What is open and closed in Rome at Christmas
Christmas Day in Rome is a real shutdown, and it catches visitors out every year. Most of the big sights close, the shops close, and the metro runs a reduced service. Plan Christmas Day itself as a church, square and lunch day, and put the Colosseum and the Vatican Museums on the days either side.
| Date | Closed | Open | Do this instead |
|---|---|---|---|
| 24 December | Vatican Museums close early at 15:00, last entry 13:00; municipal museums 09:30 to 14:00; shops close early | Colosseum, Pantheon, churches, Piazza Navona market, St Peter's Square | Book a morning sight, then the Navona market and lights in the evening; Christmas Eve Mass in the evening |
| 25 December | Colosseum, Vatican Museums, Pantheon interior, Borghese Gallery, shops, most cafes | Churches, St Peter's Square, restaurants with Christmas lunch reservations, some bars, a handful of pharmacies | Urbi et Orbi at noon in St Peter's Square, churches, a long walk through the centre, a booked Christmas lunch |
| 26 December | Vatican Museums | Colosseum and Roman Forum reopen; shops reopen; Angelus in St Peter's Square | Colosseum day, then the Angelus and an evening in Trastevere |
| 31 December | Vatican Museums close early at 15:00, last entry 13:00; municipal museums 09:30 to 14:00 | Colosseum, shops, restaurants, Piazza Navona market | Morning sights, then the free New Year's Eve concert at Circo Massimo |
| 1 January | Colosseum, Vatican Museums, most shops | Churches, St Peter's Square, restaurants with New Year's Day lunch reservations | A slow day: churches, the square, a walk along the Tiber, a long lunch |
| 6 January | Vatican Museums; Priscilla Catacombs | Colosseum, shops, Piazza Navona market, churches | Colosseum in the morning, then Piazza Navona for the Befana finale |
Christmas Day itself deserves a plan of its own. Start with the Urbi et Orbi blessing at noon in St Peter's Square, then walk the centre: the churches are open, the streets are quiet, and the lights are on all day. Book Christmas lunch well in advance, as restaurants that open on Christmas Day run set menus and fill up weeks ahead. Past menus at Hosteria Grappolo d'Oro, Proloco Trastevere and Osteria Fratelli Mori ran to about 60 euros per person. If you have not booked, your fallback is a self-catering apartment with food bought on 24 December, or a hotel restaurant.
The days around Christmas are easier. The Colosseum and the Roman Forum close on 25 December and 1 January and reopen on 26 December, and they are open on 6 January. The Vatican Museums close on 8, 25 and 26 December and on 1 and 6 January, and run shortened hours, 08:00 to 15:00, on 24 and 31 December.
Getting around Rome at Christmas
Rome at Christmas is a walking city, and the centre is compact enough to cover on foot. Piazza Navona, the Pantheon, the Trevi Fountain and the Spanish Steps are all within a 20-minute walk of each other. The metro and buses matter mainly for the Vatican, the Colosseum and the airport.
The metro is the part to plan around. On Christmas Eve, 24 December, the metro runs until 21:00. On Christmas Day, 25 December, it runs a split service: it stops in the afternoon from 13:00 to 16:30 and finishes at 21:00. The morning start time on Christmas Day is disputed, with 05:30 and 08:30 both given, so check the ATAC timetable before you travel. On 26 December services run a regular holiday schedule, and on 31 December and 1 January they are reduced. No 2026 ATAC Christmas notice had been published by 9 November.
A single BIT ticket costs 1.50 euros, about 1.30 pounds, and covers 100 minutes. A 24-hour ticket costs 8.50 euros, a 48-hour ticket 15 euros, and a 72-hour ticket 22 euros, about 19 pounds. Buy tickets at metro stations, newsagents and tobacconists, and validate them on your first ride.
The Leonardo Express train runs from Fiumicino to Termini station and costs 14 euros, about 12 pounds, and it is the fastest way into the centre. A fixed-fare taxi from Fiumicino to the centre costs 55 euros, about 48 pounds, and the fixed fare applies inside the Aurelian Walls. Ciampino, used by Ryanair from Stansted, is closer to the city, with buses and taxis into the centre. On Christmas Day and New Year's Day, trains and buses run less often, so allow extra time.
| Date | Metro | Bus and tram | Airport transfers |
|---|---|---|---|
| 24 December | Runs until 21:00 | Reduced evening service | Leonardo Express and taxis running; allow extra time |
| 25 December | Split service: afternoon break 13:00 to 16:30, finishes 21:00; morning start disputed (05:30 vs 08:30) | Reduced service | Trains and buses less frequent; taxi is the safest option |
| 26 December | Regular holiday schedule | Regular holiday schedule | Normal service |
| 31 December | Reduced service, finishes early | Reduced evening service | Normal service, busier in the evening |
| 1 January | Reduced service | Reduced service | Trains and buses less frequent |
A 4-day Rome at Christmas plan
This plan covers 23 to 26 December, the heart of Christmas week, and it is routed around the closures and the 16:40 sunset. It assumes you are staying in the centre and walking most of the time, with the big sights booked in advance.
Day 1, 23 December, is for the ancient city. Book the Colosseum for the morning, and walk the Roman Forum and Palatine Hill afterwards. In the afternoon, walk to the Trevi Fountain and the Spanish Steps as the lights come on. Finish in Piazza Navona.
Day 2, 24 December, is for the Vatican and Christmas Eve. Book the Vatican Museums for the morning, remembering they close at 15:00 with last entry at 13:00. In the afternoon, see the tree, the nativity and the 100 Presepi exhibition in St Peter's Square. In the evening, attend Christmas Eve Mass if you have a ticket, watch it on the screens in the square, or book a Christmas Eve fish dinner.
Day 3, 25 December, is Christmas Day, and it is a slow day by design. Go to St Peter's Square for the Urbi et Orbi blessing at noon, arriving early to clear security by 09:00 to 10:00. After the blessing, walk the centre. Lunch is the main event, so book a Christmas lunch weeks ahead, or cook in your apartment with food bought on 24 December. In the evening, walk the lights along Via del Corso and end in Piazza Navona.
Day 4, 26 December, is for the Colosseum and the city you missed. The Colosseum and Forum reopen, so book a morning visit if you did not go on day 1. In the afternoon, see the Angelus in St Peter's Square, then walk the Aventine Hill. Finish with dinner in Testaccio.
For the quieter window, 27 to 30 December, the plan is simpler. Day 1: the Vatican Museums, free on Sunday 27 December from 09:00 to 14:00, then St Peter's Square. Day 2: the Colosseum and the Forum in the morning, Monti and the Trevi Fountain in the afternoon, Piazza Navona after dark. Day 3: the Borghese Gallery, then Villa Borghese and Christmas World, and an evening in Trastevere. Day 4: the Capitoline Museums, Santa Prassede and San Luigi dei Francesi, and a final walk along the lights. If you are comparing December trips before you book, see the best places to visit in December for UK travellers.
Staying to 6 January is worth it if you can. The Befana finale in Piazza Navona on Epiphany is the true end of the Roman Christmas. The Vatican Museums are closed on 6 January, so put the Colosseum on that morning and save the square for the afternoon.
Where to stay in Rome at Christmas
Where you stay matters more at Christmas than at any other time of year, because the days are short, the evenings are cold, and you will want to walk home after the lights rather than wait for a bus in the cold.
Centro Storico, the historic centre around Piazza Navona, the Pantheon and the Trevi Fountain, is the best base for first-timers. Everything is within a short walk, and you can walk home after the evening lights without a metro ride. It is also the most expensive and noisiest area at Christmas.
Trastevere, across the Tiber, is the best base for food-led evenings, with trattorias, wine bars and bakeries on every street. Monti, between the Colosseum and Termini station, is the best base for a walkable stay near the ancient sights. Prati, near the Vatican, is the best base for a Vatican Christmas: a 10-minute walk from St Peter's Square and calmer than the centre at night, but further from the markets and the lights.
Prices change sharply across the season. December is Rome's cheapest month for hotels, at about 153 euros a night on average, or about 133 pounds, according to Skyscanner. In the first week of December, central three-star rooms run 100 to 140 euros a night, about 87 to 122 pounds. By mid-month they are 150 to 190 euros, about 131 to 165 pounds. From 23 December to 2 January they jump to 220 to 300 euros, about 191 to 261 pounds. Book Christmas week at least two months ahead.
What to eat at Christmas in Rome
Roman food at Christmas is rich, seasonal and worth planning around. The city has its own Christmas traditions, and the best meals of the season are the ones you book in advance, not the ones you stumble into on the night.
Start with Rome's own cacio e pepe, the city's most famous pasta: pecorino, black pepper and pasta water, nothing else. It is the dish to order on your first night. Other Roman pastas to try are carbonara, amatriciana and gricia.
Christmas Eve dinner is traditionally fish: a multi-course fish dinner, with fried cod, seafood pasta and vegetables, and no meat. Many restaurants run a set fish menu on 24 December, and they book out weeks ahead. Christmas Day lunch is the big meal of the season: antipasti, then a pasta course, then roast meat, then panettone and torrone. Restaurants that open on Christmas Day run set menus, typically 60 to 150 euros per person, and they need booking well in advance.
Panettone and pandoro are the two Christmas cakes, and Romans argue about them. Panettone, from Milan, is tall, yeasted and studded with candied fruit and raisins. Pandoro, from Verona, is star-shaped, buttery and dusted with icing sugar.
For Christmas Eve and Christmas Day, book at least a month ahead, and confirm your booking a few days before you travel. For the rest of the season, the trattorias of Trastevere and Testaccio are the best bet: they are local, cheaper than the centre, and less likely to run a tourist menu. Avoid the restaurants with picture menus and touts on the main squares. If you are self-catering, buy your Christmas food on 23 or 24 December.
Rome at Christmas with kids
Rome at Christmas works well with children, because the season is built around things they can see and touch: lights, carousels, nativity scenes and sweets. Bring a carrier for younger children: the cobbles and crowds are hard work with a pushchair.
The Piazza Navona market is the first stop. The carousel in the middle of the square is the centrepiece, and the sweet stalls, balloon sellers and nativity figures keep children busy for an hour or more. Go after dark if you want the lights.
St Peter's Square is the second stop. The tree and the life-size nativity scene are impressive at any age, and the 100 Presepi exhibition under the colonnade is a hit with children. The evening is the best time, when the tree is lit and the crowds thin.
Christmas World at Villa Borghese is the biggest ticketed event for children, with rides, shows and an ice rink. Its best supported dates are 28 November 2026 to 10 January 2027, but its 2026 ticket price is unconfirmed, so check the official site before you go. Cinecitta World, the film-themed park south of the city, runs a Christmas season with rides and shows, and entry is included in a park ticket, usually about 20 to 30 euros. Ice rinks pop up at the main Christmas villages, including the EUR village. On a rainy day, the Explora Children's Museum, near Piazza del Popolo, is the best indoor option. Pack waterproofs and warm layers: December in Rome is mild but damp, with highs around 13C and nights of 4 to 5C.
Costs and budgeting
Rome at Christmas can be cheap or expensive, and the difference is mostly the date. The first three weeks of December are the cheapest of the year, at about 153 euros a night on average. Prices jump sharply from around 20 December to 6 January, when central three-star rooms run 220 to 300 euros a night.
Much of the Christmas season is free. St Peter's Square, the tree, the nativity, the 100 Presepi exhibition, the Piazza Navona market, the lights and the church concerts all cost nothing. The table below sets out the two sides, with pound conversions at 1 euro to 0.87 pounds.
| Free | Ticketed |
|---|---|
| St Peter's Square, tree and nativity | Colosseum: 18 euros standard, 24 euros Full Experience (arena, underground, attic) |
| 100 Presepi exhibition, 8 Dec 2026 to 7 Jan 2027 | Vatican Museums: 20 euros, 25 euros with online booking (20 plus 5 booking fee) |
| Piazza Navona market entry | Pantheon: 7 euros |
| Christmas lights along Via del Corso and the centre | Trevi Fountain access: 2 euros |
| Church concerts and Masses | Castel Sant'Angelo: 18 euros |
| 27 December free Sunday at the Vatican Museums, 09:00 to 14:00 | Capitoline Museums: from about 15 euros |
| 3 January first-Sunday free entry to state museums, including the Colosseum | Christmas World: 2026 price unconfirmed (2025 from 12.50 euros) |
| New Year's Eve concert at Circo Massimo | Cinecitta World: from 29 euros for adults, from 24 euros for children 100 to 140 cm |
One warning matters more than any price. Papal Mass tickets are free, and so is the Urbi et Orbi blessing. If a website offers to sell you a ticket for Christmas Eve Mass, it is a scam, and the prices run into thousands of pounds. The only route is the Prefecture of the Papal Household, by email or fax. The same applies to the free Sundays: the Vatican Museums are free on 27 December, and the state museums are free on 3 January. You still need to book a free ticket in advance for the Colosseum, and under-18s are free there but still need a booked ticket. Book on the official portals, 30 days ahead for the Colosseum, and never through a reseller.
New Year's Eve and the Befana: 27 December to 6 January
The season does not end on Christmas Day. The ten days from 27 December to 6 January are the quietest and, for many travellers, the best part of Rome at Christmas. The crowds thin, the prices ease, and the city keeps its lights up through Epiphany.
New Year's Eve in Rome is a free, open-air celebration. The main event is the free concert at Circo Massimo, which runs through the evening and ends with fireworks at midnight. Arrive early and expect crowds. The metro and buses run reduced services, so plan your journey home in advance.
The days after New Year are the calmest of the season. On 27 December, the Vatican Museums are free for the last Sunday of the month, from 09:00 to 14:00. On 3 January 2027, the first Sunday of the month, the state museums are free, including the Colosseum, although you still need to book a free ticket in advance. The 2 to 5 January stretch is the quietest of all.
Epiphany, 6 January 2027, is the true end of the Roman Christmas. The Epiphany Mass is traditionally held at 09:30, although the 2026 time has not yet been confirmed, and the Befana arrives in Piazza Navona in the afternoon to close the market. The arrival time is not yet confirmed for 2027: the 2026 arrival was at 14:00, while several guides give 10:00. The Vatican Museums and the Priscilla Catacombs are closed on 6 January, so put the Colosseum on the morning and save the square for the afternoon.
For a quiet winter city break after Christmas, the things to do in Ghent in January and February make a good next trip.
Conclusion
Rome at Christmas rewards the traveller who plans ahead and punishes the one who does not. The season is long, from 8 December to 6 January, and the best days are not always the obvious ones: early December for prices, 2 to 5 January for space, and Christmas Day itself for the quiet streets and the blessing in the square. Build your trip around the closures, book the Colosseum and the Vatican Museums 30 days ahead, and reserve Christmas lunch weeks in advance. Do that, and Rome at Christmas is the city at its most theatrical: lights on the Corso, the market in the square, the tree under the Basilica, and a season that ends, as it should, with a witch on a broomstick.