Late last year, what is thought to be a bat-associated coronavirus infected humans in Wuhan, a city of 11 million in China, possibly after a stopover in illegally traded pangolins—setting off a global pandemic. This kind of thing has happened before—with AIDS, SARS, and MERS, for example. Much remains unknown about the biology of COVID-19, which is alarmingly communicable by people with few or no symptoms. But an epidemic is only part biology. It is also driven by cultural factors, and urbanization is a crucial aspect. As sites of large gatherings and dense living conditions, cities offer the perfect settings for the spread of infection, yet their role seems to have often gone unremarked in discussions of the pandemic.