Civil War enthusiasts this weekend will get a rare glimpse at what a handful of scholars are calling the most significant find of its kind in generations: a pair of stereoscopic photos, purportedly of Abraham Lincoln at Gettysburg before he delivered his famous address.

Photos of Lincoln are incredibly rare; only about 130 exist. Until now, there was only one known photo of the 16th president at Gettysburg — sitting in a crowd of dignitaries on Nov. 19, 1863, just after delivering the legendary speech.

Photo here.