Happy birthday to Christo and Jeanne-Claude, the married artist-duo who remarkably were both born on this day in 1935.

In 1970, the artists wrapped the iconic Great Stair Hall at the Museum as a part of “PEACE,” an exhibition that prompted artists to create works that demonstrated their concerns for a world without peace.

Archival photograph of “Wrapped Stairway/Project for Main Entrance-Stair Hall in Philadelphia Museum of Art (Photograph of Realization),” 1970, by Christo