Located a few kilometers north of the village “Grotta Gigante” (Giant Cave) is famous for its main cavity called the Great Cave whose size could contain the St. Peter's Basilica of Rome. Its cavity presents a ellipsoidal shape that measures 275 meters long, 65 meters wide and a domed vault that exceeds 100 meters: such size will confer the title of biggest cavities open to the visitors of the world. For its geological aspects the Giant Cave is one of the three most spectacular karst cave as well as the only one left in Italian territory since Postojna cave and Skocjan cave are now in Slovenia. The cave belong to the Julian Alpine company that takes care of opening, lighting and providing guides services and it can be visited in around an hour during the whole year. A long stairway interspersed with walkways, trails and ramps suspended in space leads to the cave base: the show is striking thanks to the skillful electric lighting system that puts special emphasis on the vault and on the reddish tint of crystalline formations, stalactites and stalagmites of impressive dimensions, such as "La Palma" more than six meters high. The Giant Cave, besides being a place of tourist interest, is also an important scientific research station: thanks to its exceptional size very sensitive instruments for the study of meteorology and microclimate underground, physics land and karst have been located inside the cave.
Next to the entrance a low building was equipped as Speleological Museum and it houses a mineralogical and anthropological selection.