Speaking of Valley Forge... it is known - but not advertised - that there is a time capsule placed there during a ceremony in 1878. If you ask a park ranger, they will admit to its existence but generally, they would rather it remain in obscurity to prevent someone from digging it up in the middle of the night.

So far, there are no plans to open it and there is no documentation on its contents. How long until this time capsule is forgotten too?