Frank was a really nice host. He told us good tips of spots such as restaurants, bars near Berlin zoo, and place to get groceries so that we didn't have to worry about things.
His full furnitured house was in a perfect location in living area near Mitte and Alexanderplatz. Easy to get to the Hackechers market also. Berlin dom and museums are in walkable distance too. I could see the TV tower from the window, which made me think that 'wow, I am really in Berlin'.
Thank you and hope to be in your place again when I visit again.