CipesDesign, When I select ?site model? there is no pull down list, just the error message. I tried your method with an abbreviated contour map, 8 contours. At the end of step 4 these contours now reside on layer ?Mod-Site-DTMData? which was created automatically after using the ?2D Polys to 3D Contours? command. Highlighting the 8 contours, the Object Info tells me that they are 3D Polygons, a valid source data according to the 11.5 Help screen. Clicking on the ?Site Model? under AEC only brings up the error message. Nothing else. I have tried using 3D loci but get the same result.