In the heart of the Milky Way, a massive black hole exerts a gravitational pull so intense that it warps the very fabric of space and time, creating a cosmic laboratory where scientists test the limits of Einstein's general relativity. By tracking the orbits of stars as they swing near this invisible giant, researchers at the European Southern Observatory use cutting-edge interferometry to measure the subtle distortions in spacetime, pushing the boundaries of our understanding of gravity and the fundamental laws that govern the universe.