A ceremony in which the two laboratories that comprise the Laser Interferometer Gravitational-wave Observatory (LIGO) were designated Historic Physics Sites by the American Physical Society was held on Wednesday, June 20, 2018 at the LIGO facility in Livingston, La. A plaque will also be placed at the LIGO facility in Hanford, Washington, to recognize the extraordinary efforts that ultimately led to the first confirmed detection of gravitational waves emanating from the violent and distant astronomical events, such as black hole mergers. Three physicists behind the project were awarded the Nobel Prize last year, and the experiments at LIGO have yielded proof of Albert Einstein's theory of relativity.