The atomic scale structure of a surface plays a central role in catalysis, defining the available sites for reactions. While there is now an extensive body of information about simple adsorption sites on metal surfaces, for other more complicated system (particularly insulators such as oxides) very little is known. We have recently been able to use classical bulk "direct methods" to determine surface structures with either surface X-ray diffraction or transmission electron diffraction. The method makes no assumptions about the surface structure and is truly ab initio. Asa consequence, structures that one might not find or expect using simple chemical arguments can be determined if present. One recent example is the observation of a new chemical species at a surface, cyclic ozone. The basics of the approach as well as other recent results are described.