Heaven's Gate (1980, United Artists, dir. Michael Cimino, 195 min, R) was the gigantic western that gained notoriety as a box office bomb. It cost $44M and grossed #1.5 M according to imdb. I saw it in Dallas at a UA theater and rather liked it. The scenery was breathtaking, and the story has political overtones: a struggle between established cattle interests and immigrants. Kris Kristofferson, Christopher Walken, John Hurt.
'The Movie that Ruined Hollywood' video
'Final Cut: The Making and Unmaking of Heaven's Gate'>
There is also an HBO docu about the cult Heaven's Gate: The Cult of Cults (2020) that committed mass suicide in California expecting an alien invasion.
It was started by Bo and Peep around 1974 and the mass death occurred in March 1997 after years of a monastic lifestyle