The Crow (Apsalooke) Indian Reservation is home to the Little Bighorn Battlefield National Monument. One of the USA's best-known Native American battlefields, this is where General George Custer made his famous 'last stand' in June 1876. Custer, and 272 soldiers, messed one too many times with Native Americans (including Crazy Horse of the Lakota Sioux), who overwhelmed the force in a frequently painted massacre. A visitor center tells the tale.
In summer, rangers give highly entertaining dramatic lectures about every two hours (free). The entrance is a mile east of I-90 on Hwy 212, 62 miles from Billings.