Microorganisms live everywhere on earth, including houses, schools, parks, and transit systems in our city. The Metagenomics and Metadesign of the Subways and Urban Biomes (MetaSUB) International consortium (http://metasub.org) brought together experts across many fields to explore microbial communities in built environments all over the world. In Japan, GoSWAB project was run by undergraduate students at the University of Tokyo and Keio University. We have been studied microbial communities at the University campus and public transportation systems.