From the Cave-In-Rock web site (
visit link) :
"The actual history of this imposing natural phenomenon is colorful and provocative. The first European explorer to encounter it was M. de Lery of France, who in 1729 called it caverne dans Le Roc. It was a conspicuous curiosity frequently mentioned by later travelers in diaries and journals.
Following the Revolutionary War, this immense recess came to serve as the ideal lair for outlaws, bandits and river pirates who preyed on the people traveling along the Ohio River.
One of the most ambitious of these ruthless malefactors was Samuel Mason. Once an officer in George Washington’s Revolutionary Army, in 1797 he converted the cavern into a tavern which he called the Cave-In-Rock.
From this apparently innocent and inviting position, Mason would dispatch his cohorts upriver to befriend unwary and bewildered travelers with offers of help and guidance. As they neared the cave, these henchmen would disable their boats or force them toward the yawning hollow, where the hapless pilgrims would be robbed, or worse. Few victims lived to tell their story.
By the early 1800s, following the demise of the Mason Gang, the cave sheltered the even more notorious Harpe Brothers, a pair of killers fleeing execution in Kentucky. They continued their personal reign of thievery and murder in Illinois, using the cave as hideout and headquarters until they too were killed.
It’s interesting to note that the cave served as a backdrop for a scene in the movie “How The West Was Won.” The scene was a near-accurate portrayal of how, in the 18th and 19th centuries, ruthless bandits used the cave to lure unsuspecting travelers to an untimely end.
Although other desperadoes continued to take advantage of the secrecy and seclusion afforded by Cave-In-Rock, by the mid-1830s the quickening westward expansion of civilization and the steady growth in the local population and commerce had destroyed or driven out the “river rats” and the cave began to serve as temporary shelter for other pioneers on their way west. Throughout the 19th century, this remarkable geological feature was an important landmark, prominently displayed on maps from the period.
In 1929, the State of Illinois acquired 64.5 acres for a park that since has increased to 204 acres. The well-wooded, 60-foot-high hills and the rugged bluffs along the river - commanding expansive views of the famous waterway - became Cave-In-Rock State Park.
In the words of Illinois historian John W. Allen, “Today only the natural beauty of the historic spot remains, clothed in mystery. In the hollow silence of the cave that echoes the peaceful cooing of doves, a visitor can let a vivid imagination run riot. But he can dream little that will be beyond what actually happened.”"