It looks like the remains of some futuristic cult. This slowly-eroding cement pyramid in Nekoma, North Dakota is all that's left of a $6 billion nuclear launch facility created as part of the Safeguard Program.
The pyramid itself was a radar system for tracking any incoming Soviet missiles that might be coming in over Canada. Silos containing surface-to-air missiles studded the grounds of the facility, ready to deliver their payloads to enemies of the U.S. during the Cold War. A huge maze of tunnels snaked beneath the surface of the ground.
The facility itself, designed by Bell Labs and Western Electric for the U.S. Army, was only operational for three days in 1975. It was shut down hastily over concerns about safety, and its tunnels were flooded.
When future archaeologists discover it, who knows what they'll think we used it for?
Read more about the pyramid on Atlas Obscura