It was so great to stay at Frank's apartment. Firstly, Frank was a very nice host, he showed me about the quarter and told me about some "must-go" places. Secondly, apartment was in a very good location, 5minutes walking from Alexanderplatz, and there is a open-market just next to the apartment, and also two supermarkets. Lastly, Frank was really attentive and helpful, one time I left the key in the apartment and he just came to me in 10 minutes! It was really impressive and I really appreciated about it. I would definitely recommend Frank as a very nice host and the apartment as well.