Uranus is one of the most under-explored and least understood planetary magnetospheres in our Solar System yet the unique system geometry and ambient solar wind conditions conspire to produce a system that is fundamentally different to other planetary magnetospheres in our Solar System. Understanding from Earth’s magnetosphere provides partial or only qualitative explanations for some features observed in Voyager 2 data and in some cases cannot explain the data, highlighting fundamental gaps in our understanding. This demonstrates that there are a range of key questions in heliophysics that are best addressed at targets other than the terrestrial magnetosphere and interplanetary/interstellar space. A Uranus Flagship mission has been identified as a top priority in the Planetary Decadal Survey and will arrive during equinox conditions at Uranus. This will provide an opportunity to study a pole-on magnetosphere over an extended period of time, studying its dynamics, diurnal variability, and evolution as season progresses towards solstice with a return to Voyager 2-like conditions. Uranus is a unique natural laboratory for testing and developing fundamental theories of space physics that will provide insight into universal magnetospheric processes in our solar system and beyond. In this White Paper we urge Heliophysics to support such a Flagship mission which will provide new insights into how magnetospheres work and important data on the outer heliosphere.