We describe PhotoCompas, a system that utilizes the time and location information embedded in digital photographs to automatically organize a personal photo collection. PhotoCompas produces browseable location and event hierarchies for the collection. This organization is created using algorithms that interleave time and location to produce an organization that mimics the way people think about their photo collections. In addition, our algorithm annotates the generated hierarchy with geographical names. We tested our approach on several real-world collections and verified that the results are meaningful and useful for the collection owners. Categories and Subject Descriptors H.3.7 [Information Systems Applications]: Information Storage and Retrieval—Digital Libraries; H.5.1 [Information Systems Applications]: Information Interfaces and Presentation—Multimedia Information Systems General Terms Human Factors, Algorithms Keywords Photo browser, geo-referenced photos, GPS, personal p...