Uptown Underground projects a geographically accurate view of the cityscape above a subway car onto its ceiling as it moves under New York City. Installed without permission, the intervention uses GPS and accelerometer data synced to projectors and microcomputers along a 6mi/25min loop. As the window for installation is only 45s, the build was designed for ultimate fluidity. Becoming aware of such a dynamic perspective offers restored connection with and newfound contextualization within the city: riders tend to put down their phones, and with wonder, look up.