A set of tall pillars and alcove-like rooms that are significant to the Miami people of Indiana.

Plans for this peninsula included houses, the United Nations Headquarters, and a nuclear power plant. When none of them worked out, it became an expansive park.

The hidden "ballroom" under a mansion lake was built by a criminal who ate a cyanide pill during his trial.

A castle built by an eccentric medieval enthusiast in rural Ohio.

Faces carved into the cliffs create an otherworldly walking trail.