In February 1942, searchlights locked onto a strange object over Los Angeles, triggering a massive anti-aircraft barrage. Many believe it wasn’t an enemy plane at all.

Across the U.S., along highways and backroads, are attractions that range from the oddly charming to the downright puzzling.

Throughout history, there have been photographs that leave scientists, researchers, and skeptics alike struggling for answers. "Strange and Haunting Photos That Continue to Puzzle the Scientific ...