The defining constraint of December is daylight: the sun is only up from roughly 08:00 to 16:30, and temperatures hover around freezing with a real chance of rain, sleet or snow. That makes the winning formula simple — one outdoor highlight, front-loaded into the light, plus one warm indoor highlight, with the evening saved for atmosphere. Trying to stack a summer-style itinerary onto a short, cold day is the main way visitors end up disappointed; leaning into the cosy rhythm is the way to enjoy it.
The festive core is the Christmas market in Piața Constituției, in front of the Palace of the Parliament — a giant lit tree, a panoramic wheel, a covered ice rink, Santa's House and around 120 chalets of mulled wine, gingerbread and crafts. The 2025–2026 edition ran 29 November – 28 December, broadly midday to 22:00 on weekdays and from 10:00 at weekends. Around it, the city's indoor culture is at its best: the George Enescu Philharmonic's season fills the Athenaeum, the big museums are calm and uncrowded, and Therme București offers a warm-water escape just north of the city.
One thing to watch is holiday hours. Around 24–26 December and 1 January, many museums close or shorten their hours, and some restaurants shut on Christmas Eve and Day; the market, Therme and major restaurants generally keep going, but it pays to confirm the exact days you are visiting. Note too that several headline museums close on Mondays (and some on Tuesdays) year-round. And 1 December — National Day, Great Union Day — brings a military parade at the Arcul de Triumf and a festive, flag-lined centre, a memorable bonus if your trip overlaps it.