Colossal Cave, Show cave and museum in southeastern Arizona, United States.

Colossal Cave is a limestone cavern containing multiple miles of continuous passages lined with stalactites, stalagmites, and patterned rock formations. It functions as both a show cave and museum where visitors can explore the geological features and learn about the underground system.

Indigenous peoples including Hohokam, Sobaipuri, and Apache used the cavern for shelter and ceremonies between 900 and 1450 AD. Centuries later, it became known as a legendary refuge during train robbery events in the 1800s.

The site carries stories of fugitives who sought shelter in its passages during the 1800s, making it a notable part of local legend and regional history. These tales have shaped how visitors experience and understand this place today.

The cavern stays at a steady temperature throughout the year, so visitors should dress appropriately for cool underground conditions. Guided tours are offered regularly and can accommodate different fitness levels.

Scientists estimate the system extends far beyond what has been mapped and opened to visitors. This means the passages you walk through represent just a small fraction of the entire underground network below the surface.