In 1964, Mike Mitchell was an 18-year-old photographer on assignment for a little known magazine, when he scored a press pass to a concert that would make history.

Photographer Mike Mitchell with one of the Beatles 1964 Washington concert photos.

It was February 11, a few days after the Beatles arrived on their first U.S. tour, and the band was playing its first North American concert at the Washington Coliseum in the nation’s capital. Mitchell had unrestricted access to the stage that night and snapped scores of black-and-white photos. He put the negatives in a box, stored it in his basement, and forgot about them for almost 20 years.

Now the photos from that historic evening are going on the auction block at Christie’s New York. And they’re a sight to behold.

Mitchell photographed the Beatles individually and as a group, catching the essence of their appeal in sharply-focused, backlit images that he digitized years later and copied back into gelatin silver prints. Christie’s is offering each of the prints individually — only one per negative — at starting prices of between $1,000 and $6,000. Officials at the auction house say they expect the photos could fetch far more.

To see the photos and get more information on the auction, click here.