I have hypsometric map/model of mountain which I get by contour lines with Z value. Can you explain how to visualize 3d model in ArcGIS? I need to get something like nviz command in GRASS.
You need to fire up either ArcScene or ArcGlobe. They are typically installed with ArcGIS Desktop so I would imagine you already have them on your machine. If you don't have the 3D extensions (as mentioned by Brad in the comments) you could try ArcGIS Explorer which is a free viewer for both 2D and 3D data.