I am working on a video concerning the construction of The Donner Pioneer Monument and came upon this intriguing photo. It shows the Donner Memorial without the statue of the family on top. The base was hand built and the sculpture installed piece by piece.

What captured my attention was the immense cornerstone sitting next to the base. The stone was dedicated a few years before as the start of the year's long effort to get the statue up. It marked the corner of the Breen cabin, who were members of the Donner Party. We see the cornerstone in pictures taken before, during, and just after the monument was dedicated. However, sometime after that, it went missing, and no one knows what happened to it.