Berlin at Christmas is amazing. Totally get what the the others are saying about places at night, but if you go at Christmas, you won’t fall short of places. When we went I think it’s something like 46/64 (one of those haha) markets dotted about, some massive, some smaller but still bigger than what we have in Manchester. We did 4 days and didn’t stop with all the historical stuff along with the markets. I’d seriously recommend it to anyone.