While the field site view of the city dominated much nineteenth-century urban health research and governance, a laboratory view of the city emerged in parallel to the rise of germ theory, bacteriology and laboratory science more generally. Laboratory science is credited with some of public health's greatest modern successes, such as vaccinations, immunizations and treatment of water and waste but, as I explore in this chapter, the laboratory view also had a great impact on the design and governance of cities which contributed to a perpetuation of urban health inequities in both rich and poor cities around the world.