The Pentagon squats across the Potomac River from Washington D.C. like a beige, concrete cookie cutter. Yet the drab building was the beating heart of America’s operations in the Vietnam War. And in the 1960s and 1970s it was a smirking, imperious challenge to hundreds of thousands of hippies nationwide.

Jerry Rubin and Abbie Hoffman were up to that challenge. Leaders of anti-war efforts during the counterculture movement, they made their name with creative, waggish stunts. The Pentagon was ripe for that treatment, and the timing was perfect. It was the end of the Summer of Love in 1967, and there was already a massive demonstration planned for the Lincoln Memorial on October 21 of that year.

But a simple march wasn’t enough — they needed something to titillate the media, an event that would draw both cultural spectators and serious revolutionaries. And by then, everyone needed a good laugh.

It was settled, then. They would perform an exorcism on the Pentagon, and at the same time levitate the building 300 feet in the air.

To figure out how many hippies it would take to encircle 6.5 million square feet military office space, Hoffman and and a friend alternated holding hands, counting body lengths as they circled the building.

“Everybody knows that a five-sided figure is evil,” explained Hoffman. “The way to exorcise it is with a circle.”

Before long security guards rushed out of the Pentagon and arrested them for littering. (They had put some leaflets on the windshields of cars in the parking lot.) They were brought before a General Services Administrator, at which point the pair explained they would like to obtain a permit to levitate the Pentagon 300 feet. By forming a circle and chanting Aramaic exorcism rites, the monstrosity would “rise into the air, turn orange, and vibrate until all evil emissions had fled. The war would end forthwith.”

According to Time magazine, a compromise was reached in the end: a permit was granted, but it only allowed a maximum levitation of 10 feet. The littering charges were dropped.