This first zipped file contains many nice prefabs which are easily included in your map/design. In MOHRadiant, just use the load command from file menu and select a prefab.
I always unzip my zipped prefab files into a folder in my main called "prefabs", then they can be found/managed easily.
Include are prefabs for
Arches, Barn, Bridge, Guard House, House, Road Curve, Steel works, Warehouses, Windmill, and Wooden hut.
Mappers HINT: Prefabs extention (.pfb) can be rename to .map extention and the file opened directed in MOHRadiant, once you place it in your main/maps/dm folder.