I haven't worked on this in a while, but here we go:
The stairway from hell. Before you call me crazy, I actually took this design from real life. The stairway runs from the top almost all the way to the bottom of the dam.
Looking down the spillway to the water about 200 or so feet below.
Looking across the open floodgates with canyon walls starting to take shape.
The whole thing. The real dam I took this from has 16 floodgates, but I figured it was already big enough as it is, so I cut it down to 12.
I started this as a CS map originally, but it has since grown way too big to work (the round would be half over in the time it takes to get anywhere). So I'm thinking of putting it HL with the buggy and the fanboat to drive around with. I just gotta figure out a way to keep the textures.