Gravity may seem elementary. But proving Einstein's theories about it is quite hard. To do so, scientists are struggling to capture gravity's most elusive hallmark: the gravitational wave. This Astro Feature focuses on research at the Laser Interferometer Gravitational-Wave Observatory (LIGO) in Livingston, LA, where scientists have constructed a sprawling facility dedicated to the detection of minute changes in spacetime caused by gravitational waves traveling from energetic events in space.