Xhizors' GM_DesertWalls is a desert build map with a very rough terrain.
It reaches the Source engine's limit for the size a map can be, so it's got a lot of room to work around in.
It contains mostly sand, as to be expected in a desert, but contains a Stonehenge-like structure in the center, with a block that if you stand on it, you get sent to the top of the map to be sent to your doom.
Oh, yeah, and the author says there's a really hard to find easter egg in this map, see if you can find it!
Download it here:
For a lot more information on this map, and to get support for it, check out its forum thread.[...]