On the northwest side of the castle hill is the entrance to a secret cave. Directly beneath the castle there is an amazing underground world, which in 2003 revealed an interesting secret. It was discovered by cavers and archaeologists. At the end of a narrow crack they came upon human bones, leather pouches, several coins, and pottery shards dating from the 1st and 2nd centuries A.D
On the rocky plateau, where today stands Spish Castle, once stood an extensive settlement belonging to people of the Púchov Culture. These people actively engaged in trade activities and maintained pure trade links with the global power of the time – Rome. At some point towards the end of the second century, the owner of these coins, probably a respected trader, was overtaken in these lands by some unanticipated events and looked for a place to hide. He found it in the depths of a dark cave that was accessible from above. Maybe he crawled in intentionally; maybe he was unlucky enough to fall, we will never know. We can be certain, however, that he never got out. He remained imprisoned in the cave and died as a result of fatal injuries. For many centuries he has guarded his property, which for that time is considerable – leather pouches, out of which, just like in a fairy tale, have spilled some silver Roman coins. Thus the secret of the cave has finally been disclosed, bearing testimony to the significance of these lands even in the most ancient of times.