More than 300 feet high, 900 feet long, and 200 feet wide, this gigantic cave is filled with spectacular stalactites and stalagmites. The required tour takes 50 minutes. Bring a sweater to ward off the year-round chill and be willing (and able) to descend 500 steps and then climb back up. To get here you can take Bus 42, which leaves every 30 minutes from the Piazza Oberdan. A more scenic route is to take the tram uphill from Piazza Oberdan to Opicina, where you connect with Bus 42.
10 km (6 miles) north of Trieste, Trieste, Friuli Venezia Giulia, 34010, Italy