Get rid of the restrictions on height, and build 50 - 100 floors Hong Kong style, at least in the center.
Tempelhof shows the stupidity of the Berlin voter. The refusal to develop even a small part of the airfield was almost exclusively justified with fears of "gentrification". Congratulation voters, you have just voted yourself into higher rents. (Also, one could have a new "Volksbefragung", in the light of the dire need for more housing in Berlin.)