Liam Mcnamara built The Clockworks for the Burning Man festival waaay back in 2005. A 3 story tall all wooden, working, click-tocking time-keepin' clocktower, and then burned it to the ground at the end of the week. Yes, even the clockwork gears were CNC routed out of wood. 

It was  back when SP was in it's infancy (or adolescence, depending on who you ask), and so never quite got the outside recognition it deserved. If you havn't seen it before, there are quite a few photos on Flickr  (of both the structure and it's fiery destruction) and a couple on his site.