The Grotta Gigante, also known as the Giant Cave of Trieste, is located near the village of Sgonico, about 15 km from Trieste.
The total length is 380m, the total depth 160m. The hall is 98.50 m high, 76.30 m wide and 167.60 m long. Since 1995 the Grotta Gigante has been listed in the Guinness Book of Records as the largest show cave in the world.
On 5 July 1908, the guided tour began, at that time with candles and Bengali lighting. However, tourism only began after 1957, when electric lighting was installed.