Not much of a "find", since it's obvious to anyone driving Alaska's McCarthy Road to visit the old Kennecott mine in Wrangell-St. Elias National Park & Preserve. But here's an old railroad trestle parallel to the road (rail line abandoned 1938, with the road later built on or along the old trackbed):
looks like it could collapse at any moment
Looks rickety. But until 1938, it carried heavy ore trains with no issues. Now, it only has to support its own weight.
The National Park Service lets pedestrians walk under the trestle, but not on it.