What is the United States National Register of Historic Places anyway?
In 1966, the National Historic Preservation Act established the National Register as "the United States government's official list of districts, sites, buildings, structures, and objects deemed worthy of preservation... These include National Historic Landmarks, National Historic Sites, National Historical Parks, National Military Parks/Battlefields, National Memorials, and some National Monuments."
So you wouldn't think that things in the National Register of Historic Places would move, but some objects do. "Objects" can include things such as monuments, sculptures, and fountains. But, aside from objects that move in place (like docked historic ships) or can be moved (like highway markers) there is one thing on the Register that moves independently throughout a town on a daily basis.
Any guesses on what it could be?
Answer: The San Francisco Cable Car System
Oddly enough, it is officially considered a "Structure". It's the only transportation system on the Register, added in 1966. That's pretty impressive, considering that there are over 85,000 places registered!
Congratulations on 134 years of making history!