We had a terrific time at Alexander's place. Though it is a basement apartment, the ceilings are high and we heard absolutely no noise from above. The apartment is well equipped, and the location is great -- very walkable, and the corner store just up the street had everything we needed to make our own breakfasts, including fresh pastries every morning. We were able to walk to everything we wanted to see. I especially want to thank Alexander for his incredibly responsive communication. I had a little trouble figuring out how to get in the place when I first got there (it was dark, we'd been traveling all day, and I was tired) and he responded quickly and clearly. Highly recommend, and we would go back if we are ever in Berlin again.