The Mammoth Site is a fascinating museum and active paleontological site in the town of Hot Springs, in the Black Hills, South Dakota, USA. It's quite special, being the largest collection of in-situ mammoth remains in the world. Sheltered within the building is an ongoing excavation of a prehistoric sinkhole filled with the remains of Pleistocene animals and plants preserved by entrapment and burial about 140,000 years ago. Since mammoth bones were found here accidentally in 1974, the remains of 61 mammoths have been recovered (including 58 North American Columbian and 3 woolly mammoths as of 2021).