Lazaretto: How Philadelphia Used an Unpopular Quarantine Based on Disputed ScienceHow the controversial practice of quarantine saved nineteenth century Philadelphia after a series of deadly epidemics. In the 1790s, four devastating yellow fever epidemics threatened the survival of Philadelphia, the nation's capital and largest city. In response, the city built a new quarantine station called the Lazaretto downriver from its port. From 1801 to 1895, a strict quarantine was enforced there to protect the city against yellow fever,