It's an ancient legend: Located in scattered areas of Earth are openings, doorways, gates, if you will, to some unseen underworld, also variously referred to as hell, Hades and Dante's Inferno.

Researchers exploring the famous Twins Cave outside of Jerusalem have uncovered evidence of some pagan rituals, dating back to the Roman Empire, that suggest people may have believed the cave was a portal to this underworld.

Bar-Ilan University archaeologists found 42 clay lamps -- dating to the late Roman period -- in a 70-foot-long vertical shaft inside the cave. It's speculated that the lamps may have been used in ancient rituals between the 2nd and 4th century C.E., to supposedly guide the Greek goddess Demeter into Hades to search for her missing daughter.

"In the ancient world, it's tricky -- if not dangerous -- to try to assume that we know what the people really thought," said Daniel Schowalter, a professor of religion and classics at Carthage College in Wisconsin.

"Even if there were rituals going on at the site, associated with the underworld, people probably knew that it was just a cave," Schowalter told The Huffington Post.

The idea of some mysterious, menacing dark world of the dead has been written about for as long as humans have speculated about it. Even still, Schowalter says most people don't understand the difference between the terms hell and Hades.

"It's called the realm of Hades, where Hades is the king," he said. "In Greek and Roman conceptions, it's a different understanding than what Christians later developed in terms of hell as a place of punishment.

"Hades was the world of the dead -- the place where the dead lived. The expectation was that when you died, you passed into a different form of life."

Schowalter is the co-director of an excavation site of a Roman temple in northern Israel. He explains the early belief that when you died, "you went to live in the place of the dead, which is the underworld, a kind of shadowy place, which did not necessarily involve punishment, and you weren't sent there because you were bad. It's just where dead people went."

But how would one actually reach this mysterious underworld realm?

According to the online edition of Israel's Haaretz, "dark, deep pits or caves were considered gateways to hell and were often used for rituals dedicated to pagan gods."

Numerous books, movies and television shows have depicted the dark, shadowy underworld. But is there any truth to the idea that an actual entrance to such a place may someday be discovered?

"My quick answer is no," Schowalter said. "The more interesting thing is that people wanted to have contact with the world of the dead and they did somewhat extreme things and developed rituals in which they thought that they could try to do that."

The whole idea that people in "hell" are being punished for various sins is, according to Schowalter, something that stems from a Christian re-interpretation of that material.

"There was this desire to have contact -- and it's obviously still seen in our society today -- where people will go to great lengths to try to understand what dead people would say to them.

"There were lots of different ways in which the ancient Greeks and Romans understood themselves connected to the gods, and they acted those out in rituals that took a lot of different forms."