We had an great time at Christian's place. The apartment is located in Prenzlauer Berg, a super nice neighborhood in Berlin, and transportation was just around the corner.
The appartment is very quiet. The room is in front of the rail line, but when we closed the window it was very quiet.
The balcony was agreeable to enjoy the sun.
Everything was sparkling clean, and the kitchen is very well furnished so we could cook and take breakfast at home.
Totally recommended !