Running a country is a high-stakes job, especially if that country is one as powerful as the United States. So, it comes without saying that its government is always hard at work behind the scenes to keep its citizens safe. That, over time, has led to some pretty intriguing (sometimes downright terrifying) classified projects.

From UFO building plans to scrapped attempts at starting a war, here’s a list of some of the top-secret operations the American government tried to hide from everybody. Declassified after decades, these photos show you a different side of history that they didn’t teach you in school.

A ‘50s-Era Supersonic Flying Saucer

Remember those alien sighting stories you heard when you were a kid? Well, they might be true…sort of. Those flying saucers people spotted in the ‘50s were likely just one of the prototypes made by the United States Air Force (USAF) and the aircraft company Avro Canada as part of Project 1794.

While it’s unsure whether the supersonic flying saucers imagined by this partnership ever took off, we found a photo of one. This is the Avro Canada VZ-9AV Avrocar on display at the USAF museum today. Its circular shape looks awfully familiar, huh? Safe to say, it’s pretty easy to mistake it for an alien UFO in flight.