The American Physical Society (APS) has designated the two facilities of the Laser Interferometer Gravitational-wave Observatory (LIGO) historic physics sites . LIGO made history in 2016 when it made the first direct detection of gravitational waves—ripples in space and time. At a dedication on June 20, 2018, in Livingston, Louisiana, two plaques were presented—one for each of the twin LIGO observatories in Livingston, Louisiana, and in Hanford, Washington.