Cities within Buildings is a project that aims to create and strengthen communities through unusually programmed buildings. The program of a City within a Building (CwB) and the adjacencies of spaces make for an immersive community experience that typically programmed residential, commercial, or mixed-use public architecture can’t achieve. A CwB can take many forms. In the case of this project the designed CwB, located in Chicago, IL, serves primarily as a residence, though has ample commercial, recreation, and functional program for both residents and non-residents. The goal of programming these functions all under one roof is to create a tight-knit community, one of which may be found typically in a suburban or even rural small town. To create this feeling in a dense city center may drive more unique residents into rental units, or keep young adults in the city center. The greatest form of sustainability is density, though as it currently stands, density can be seen as unattractive for various reasons. The CwB aims to solve this by providing ample outdoor space, opportunities for interaction with the site, and localized markets and vendors to bring a sense of community into the dense city of Chicago.