This paper describes the features and capabilities of the Multi-Axial Subassemblage Testing (MAST) System at the University of Minnesota, which is one of the large-scale testing facilities awarded under the George E. Brown, Jr. Network for Earthquake Engineering Simulation program, funded through the National Science Foundation. The MAST system enables multi-axial quasi-static cyclic tests of largescale structural subassemblages including portions of beam-column frame systems, walls, and bridge piers. One of the key features of the system is the employment of an advanced six-degree-of-freedom controller, which can be used to apply deformations and loading in a straightforward and reproducible manner, including the capability for mixed-mode control. The system also features state-of-the-art telepresence capabilities to collect sensor data, still camera images, streaming video and audio data. The MAST system advances the current state of technology by allowing the experimental simulation of complex boundary effects through its multi-axial capabilities, which can impose multiple-degree-offreedom states of deformation and load. The system is unique in size and scope and will greatly expand the large-scale earthquake experimentation capabilities both nationally and internationally.