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.

In the 1950s, America and Canada teamed up to build the Avrocar - a real flying saucer. Engineered with a circular ...