Underworlds is a cross-disciplinary, open-data platform for monitoring urban health patterns, shaping more inclusive public health strategies, and pushing the boundaries of urban epidemiology. Pioneered by the Senseable City Lab and the Alm Lab, and sponsored by the MIT-Kuwait Center for Natural Resources and the Environment, a prototype smart sewage platform is being developed at MIT consisting of physical infrastructure, biochemical measurement technologies, and the down­stream computational tools and analytics necessary to interpret and act on our findings.