A Colorado courthouse that held the United States’ first same-sex marriage has been added to the National Register of Historic Places. The now federally recognized Colorado Boulder County Courthouse held a gay marriage way back in 1975 when it issued a marriage license to a same-sex couple when they came in and asked for one. The clerk at the time, Clela Rorex, issued six marriage licenses during the time as news spread. The sate’s attorney general ordered her to stop issuing the licenses and ultimately stripped them of their legality.

Now, the courthouse, which very much is still standing, will have a marker remembering this historic moment in LGBT history.