When developing algorithms for coordinating the behaviors of swarms of robots it is crucial that the algorithms are actually deployed and tested on real hardware platforms. Unfortunately, building and maintaining a swarm robotics testbed is a resource-intense proposition and, as a consequence, resources rather than ideas tend to be the bottleneck and swarm robotics research does not progress at the rate it could. The Robotarium sets out to remedy this problem by providing remote access to a large team of robots, where users can upload their code, run the experiments remotely, and get the scientific data back. This article describes the structure and architecture of the Robotarium as well as discusses what constitutes an effective, remotely accessible research platform. This paper won the IEEE Robotics & Automation Best Multi-Robot Systems Award at ICRA 2017.