.Map :: MoHAA Mapping

how do i make these "things" there :S

One way is to make the arch like this:
http://www.carbongraphx.com/mohaa/vidtuts.html

And then use the clipper tool on the outside to round it off.

That arch was made from two Curve > Primitives > Square Cylinders that are 16 units square.

If you get a decompiler, You can copy those arches from the Southern France map.