Now that I think of it, a big hydro dam would be perfect: power and cooling in one place.
Downtown Los Angeles: The One Wilshire building, which is the worlds most connected building. There are over twenty floors of data centers. I used Corporate Colo which was a block or two away. That building had at least 10 floors of Data Centers.
Every DC I’ve been in (probably around 20 in total) has been multi storey.