The UMass Amherst Diverse Outdoor Mobile Environment (DOME) test bed consists of approximately 35 computer-equipped buses and a mesh network built in cooperation with the Town of Amherst. Each computer on a bus, referred to as a brick, has a WiFi PCI card and a separate WiFi access point, a 3G modem, a proprietary 900MHz radio, and a GPS device. We built the system because mobile systems research is affected by many variables, encompassing environmental interference, throughput and latency, movement, connection establishment and node discovery, to name just a few. The test bed allows us to measure, identify, and validate these variables and evaluate novel systems in a large scale environment. Users construct experiments as virtual machines that are uploaded and executed on each bus.