The Hearst Tower in New York is a very nice combination of an Art Deco stone building and a modern tower built on it base on a triangular structure ( http://www.fosterandpartners.com/projects/hearst-tower/ ).
In this MOC, the triangular structure is suggested using the equilateral Road Sign triangular part but, because the triangles of the real tower are not equilateral, I have introduced more levels.
NY Hearst Tower (AVD) by Daniel Stoeffler, on Flickr
NY Hearst Tower (ARG) by Daniel Stoeffler, on Flickr
NY Hearst Tower (base) by Daniel Stoeffler, on Flickr
Enjoy