I am planning on making a University of Texas Themed cake in a few weeks. Planning a sheet cake with the Longhorn Symbol on one side flat on the cake, probably made from Fondant cutout and the UT Tower standing erect on the other side of the cake (around 10 - 12 inches tall /not counting the top of the tower/ )

My problem is that I have never constructed a standing object on the top of the cake and I am not sure of the best approach. Considering the following options:
1)Styrofoam and just decorate it (however I would truly rather have something edible)
2)Rice Crispie Treat Tower covered with Fondant

However I really want to make it entirely out of cake -

3) Cake (If I do make the entire tower out of cake -How can I ensure that it would be stable and what is the best way to stack the cake?).

All suggestions are truly welcomed!
Thank you!

see this thread for cake that looks like Big Ben in London.

http://forum.cakecentral.com/cake-decorating-ftopict-22586-ben.html

and the final result: http://www.cakecentral.com/cake-photo_41531.html

It's a traditional multi-tiered cake -- BUT all the tiers are the same size. (well except for the very top of the tower)

standard internal supports

may want to do concept like you see in so many cake challenges of having the cake slip down over a central support

http://www.cakecentral.com/cake-photo_1420079.htmlv

Really great links and ideas! I was just baffled! Thank you!