In the municipality of Crespadoro the archaeological finds that are surfacing on the Purga of Durlo (purk, burgh = castle or fortified place, characteristic volcanic cone perfectly regular) bring back to historical periods far away.
Just above the rocks of the eruptive mouth, there are the ruins of a tower. The popular legend associates it with the remains of an ancient castle.
A little lower, all around, traces of walls to protect the stronghold.
But the archaeological traces go well beyond. It is possible to hypothesize the continuity of settlement since the Iron Age and, certainly, here there was a prehistoric castelliere, then used as a Roman castrum and finally as a strategic Longobard post.