In the first season of K-On there's a quick shot of Yui's parents in front of Brandenburg Gate (Brandenburger Tor) in Berlin, so I went to Germany to take a look.
Image from S1E7 - 06m34s
Yui's parents spending their Christmas in Germany.
Image from S1E7 - 06m31s
Closeup of the top of the gate.
No map since this is a famous tourist attraction.
This location was visited on 2018/08/17.