The inhabitants of the Valleys of Natisone, for a long time they believed this symbols ware the playground for a common table game. The Tria game). The most widespread theory is that this symbol, existant in other parts of Italy, represents the city of Jerusalem, and the three walls that protected the city at the age of Crusade. Following this theory, these symbols should be made by the Knights Templars, to indicate the way to the Holy Land.(to Jerusalem) I think this explanation lacks credibility, because if the "tria" had truly represented the City of Jerusalem would certainly appear in many medieval texts, but it is not. In addition, the fortress city of Jerusalem, at medieval age was located near a rocky ridge, so the surrounding walls was on three sides only, and not on four. Doing research on the meaning of this symbol, I found an interesting analogy with some ancient drawings depicting the mythical city of Atlantis. Recent studies have suggested that about the ancient civilization of Atlantis was like a Mother Culture, progenitor of all subsequent ones, existed on a continent in the middle of the Atlantic Ocean more than 3000 years ago, and then disappear because of a violent cataclysm natural. Platone, Greek historians, narrate about a big city organized under a curious geometric structure, formed by a series of concentric circles.

This Mother Culture would have left even the enigmatic pyramid building, still shrouded in mystery, inexplicably present in places very distant from them as Egypt and Mexico, and attributed to civilities which had no other things in common.

Continuing into the research I have identified similarities between the "TRIA" shape and Atlantis. The three concentric squares are like a view from the top of a pyramid, following the same concept of concentricity existing in the representation of the city of Atlantis. †
A recent incredible discovery, still waiting for final verification, is the three pyramids in Visoko, a little town near Sarajevo in Bosnia. This fact would confirm that the Mother Culture of Atlantis was existed also in Europe, and that the Tria symbols could be something from a historic period very far in time.
Iím not saying that the TRIE were created by the people of Atlantis, but that the meaning of this symbol has been inherited from a civilization more ancient, and then be reused to identify an important place, certainly a religious site. I know that the Cave of S.Giovanni DíAntro has been used as a place for paganís ceremonials.(also for the presence of a water fount inside) Analyzing the locatins of the Trie in Valleys of Natisone, it seems that they are placed along a hypothetical path, along the left side of the river, which lead to the Cave of Antro. In the village, however, I found 4 Trie; consider this symbol concentration in an small area, I believe that they are not the references (such as Vernasso, Biacis and Tercetta), but that symbolize instead the final destination, an important place for all the peoples of the valley and also for the wayfarers.