The structure and conformation of three self-assembled supramolecular species, a rectangle, a square, and a three-dimensional cage, on Au(111) surfaces were investigated by scanning tunneling microscopy. These supramolecular assemblies adsorb on Au(1 11) surfaces and self-organize to form highly ordered adlayers with distinct conformations that are consistent with their chemical structures. The faces of the supramolecular rectangle and square lie flat on the surface, preserving their rectangle and square conformations, respectively. The three-dimensional cage also forms well-ordered adlayers on the gold surface, forming regular molecular rows of assemblies. When the rectangle and cage were mixed together, the assemblies separated into individual domains, and no mixed adlayers were observed. These results provide direct evidence of the noncrystalline solid-state structures of these assemblies and information about how they self-organize on Au(111) surfaces, which is of importance in the potential manufacturing of functional nanostructures and devices.