There are many distinguishing features of the world’s great cities, and one of these features is a well-maintained and efficient mass transit system. Developed and maintained by Mike Rohde, this site pays homage to many of these systems. The site includes sections on the art and architecture of these systems, photo galleries, and a FAQ section that answers such topical queries as “What is a metro?” and “How safe are metros?” One particularly nice feature is the World Metro List, compiled by Jordi Serradell. Here visitors can browse through a list that offers some comparative data on the world’s metro system, such as the number of stations or their total length. Additionally, the area “Metros with a View” provides material on outstanding vistas that can be found on a number of systems, such as those in Stockholm and Medellin.