The limestone cave along the Ohio River became one of the most compelling features of Cave-in-Rock State Park and loomed large in popular folk tales of the Illinois frontier as a reputed robber's den and outlaw hideout. Although no evidence directly ties the cave to criminals such as the Mason gang or the Harpe Brothers, who operated in this area during the late 1700s and early 1800s, opportunists who preyed upon lone travelers may have taken shelter there or lured people into the darkness to rob them. By the mid-1800s, pioneers heading west stopped at the cave to rest, and steamboats docked nearby so tourists could visit it. The first European explorer known to encounter the cave was M. De Lery of France in 1729, and he named it caverne danse Le Roc. Before the mid-nineteenth century, lone travelers floating valuable goods along the Ohio River risked robbery or even death. In 1929, the State of Illinois acquired 645 acres for a park, and the surrounding forest, hills, and rugged river bluffs became the 204-acre Cave in Rock State Park. In 1962, the cave appeared in a scene in the film How the West Was Won.