The Grotte del Caglieron are located in Breda, a hamlet in Fregona, Treviso.

The complex consists of a series of cavities, part of which are of artificial origin and part of natural origin; for the natural part, it is a deep gorge incised by the Caglieron stream on alternating layers of calcareous conglomerate, sandstone and marl of the Middle Miocene (from 16 to 10 million years ago).

The Cansiglio, a plateau of Carniche Prealps placed between the provinces of Treviso, Belluno and Pordenone, stands with its outer slopes above the south and east of the Veneto and Friuli plain, while to the north it is bounded by the region of Alpago and to the northeast by the mountain group of the Cavallo; finally, at the west, the Val Lapisina separates it from the Col Visentin.