From the early Nineteenth Century, the residents of Franklinville thought that the cave situated along the banks of Spruce Creek ended in a small room where local settlers scratched their names and the dates of their visits—the earliest being 1816. They may also have thought that they were among the first to explore the several rooms and passages of the cave.

All that changed in 1928 when a curious and adventurous young couple made their first visit to the cave. Harold "Hubby" Wertz and his wife, Lenore, were from nearby Tyrone and were avid spelunkers. When they reached what was believed to be the deepest chamber of the cavern, Hubby observed that the room was primarily formed by erosion rather than solution. He figured that the water which had formed the cave had to have flowed somewhere from that room. He and Lenore started digging around in the clay floor and discovered a small opening, less than twelve inches in diameter—which proved to be the entrance to an extensive new section of cave. What they eventually found was to nearly triple the size of the cave system as it had previously been known.

After making their discovery, Hubby and Lenore began acquiring the land and mineral rights, hoping to develop the cavern and open it to the general public. Through careful exploration of the small entrance they'd discovered, they were able to blast through fourteen feet of limestone to discover what is now known as Giant’s Hall.

Also during early work on the cave, they began to hear some of the local lore surrounding the notorious outlaw, David Lewis. By checking local history, they realized that Lewis had a very strong link with the cave and had, indeed, used it s a hideout.

But the biggest surprise was yet to come. Hubby and Lenore had originally intended to call their new venture Franklin Caverns. However, as workmen were leveling the clay floors in the first room, they unearthed some arrowheads which proved to be over 400 years old. Construction work halted while a team of archaeologists excavated more than 500 artifacts, as well as some skeletal remains, in the first three rooms. These relics were  identified by the US National Museum as belonging primarily to the Mohawk and Lenape tribes.

After two years of excavation and a $500,000 investment, Hubby and Lenore opened "Historic Indian Cave" on June 15, 1929—four months before the stock market crash and the beginning of the Great Depression. With $50 left, Hubby, Lenore, and their two children moved to Miami, Florida, where they eventually opened an Indian trading post. From 1930 to 1941, the Wertz family returned each summer to open the cavern and each winter operated the Trading Post. During that time, they also changed the name of the cave to Indian Caverns.

Following the tragic death of Lenore Wertz in a car accident in 1941, the family settled permanently in Pennsylvania. Hubby and his son, Harold "Bear" Wertz, Jr., then aged fourteen, formed a partnership to run Indian Caverns—a partnership which remained intact until Hubby's death, after sixty years in the business, in 1987. Today, the cave is still owned and operated by the Wertz family.