Mount Elbert Witness BM (CO)
This was the one benchmark I was able to find on 8-31-08 but it is possible I missed the central benchmark due to someone sitting on it. There were about twenty people on top while I was there on a beautiful summer day. Witness benchmarks are placed to help locate where the central benchmark is placed.
See the main benchmark page to get a nice link to the "why" of benchmarks.