Communication upfront with Heinz went smooth and efficient. Actual logistics on-site were handled by the office within the appartment building, in an equally swift and friendly manner. The appartment was nice, clean and spacious enough for four guests. Situated on the top floor it means little interference from other residents. Location is perfect: very close to Brandenburger Tor and in walking distance from several sites of historic interest, bike rental around the corner, supermarket and Berlin's biggest shopping mall within a 5-minute walk. The subway station very nearby provides quick connections to other parts of the city. All in all a great place to stay.