What about building a basement and using the moveobjects cheat to place a tower down there. Then build a staircase up to the surface and build something around the stairwell.
I just gave it a go and it worked, I've upgraded the tower twice so far and things are going fine. I have an ocupancy of 40/40 and I'm making a profit of about 1,500.
You can see in this pic I have a pool, a dining room plus a reception area with toilets. The stairs going down are in the reception area. Note that this was just a slap up building job just to test the underground theory.
In this pic, you can see the tower underground.