The COSMOS project is aimed at design, development, and deployment of a city-scale advanced wireless testbed in order to support real-world experimentation on next-generation wireless technologies and applications. The COSMOS architecture has a particular focus on ultra-high bandwidth and low latency wireless communication tightly coupled with edge cloud computing. The COSMOS testbed will be deployed in upper Manhattan and will consist of 40-50 advanced software-defined radio nodes along with fiber-optic front-haul and back-haul networks and edge and core cloud computing infrastructure. Researchers will be able to run experiments remotely on the COSMOS testbed by logging into a web-based portal which will provide various facilities for experiment execution, measurements, and data collection.