Revit's older, purely geometric site-terrain element - a shape with no material layers or quantity data, superseded for most new work by the Toposolid. A Toposurface models a site's ground shape from survey points, contour lines, or an imported point cloud, but carries no material layers or schedulable quantities the way a Toposolid does. It still appears in older projects and remains useful for simple site context, but Autodesk's newer Toposolid is now the recommended tool whenever the site itself needs to behave like a real building element.