What will cities look like in the aftermath of Covid-19? What does the stress test of mass quarantine reveal about emerging dynamics in contemporary urbanism, from the platformization of public space to the new communalism of the precariat? Quarantinology is one answer to this question: a catalog of logistical interventions that explores the history of the quarantined city and speculates about its future. "There are few elements of urbanism that have not been altered by the 2019-2020 pandemic. Thermal screening and monitoring is now a routine feature on the Moscow Metro. Supermarkets in Madrid are policed by stewards who impose capacity restrictions and maintain dedicated shopping hours for vulnerable groups. In France and Italy, an “attestation” is required for non-essential journeys. Drones heckle crowds in Belgian parks who fail to keep a safe distance and robots at Futian Station in Shenzhen rebuke travelers without masks. While the logics of quarantine remain the same, the technologies by which it is deployed have changed." "Covid-19 has proven timely to produce, difficult to scale, and unevenly distributed—technological systems that track symptoms and risk of exposure have been much faster to develop and deploy. Faced with the triple bind between preventable mortality, state or corporate biosurveillance, and economic ruin, many have chosen to rewire existing sensing mechanisms with varying degrees of user consent." "Of course, there is a danger that this sensing infrastructure will become a barrier itself, a tool capable of conditioning behavior beyond that which is necessary to combat disease. But too much focus on a technological fix coming down the pipeline—whose efficacy will always be contingent on proper use and complementary forms of sociality—means failing to recognize the immunological defenses being prototyped elsewhere."