Not bad, it looks like it could be fun to play.
It´s technically okay too, the temple pillars save it in terms of occlusion.
You have lots of unused heightfields.Those make the poly load higher, because there are unseen side faces generated nevertheless for those.
So where ever you have green cubes, but they aren´t used, use G to "un-heightfield" them.
Also, you use some very bright lights. Check the mappers_readme.txt for lightning suggestions.
I really need to make some extra architectural models I guess, the bridge´s uv´s aren´t suited for the standard texture dimensions...