The visit to Grotte di Castellana, open all year, is carried out with the help of tour guides. The route runs at an average depth of 70 meters along two routes: the first with a length of 1 km and lasted 50 minutes, the other with a length of 3 km and lasting almost two hours. The temperature of the underground environments, constant throughout the year, is of about 18 ° C, while the humidity is higher than 90%. Grave, first and most extensive cave of the underground system, is the only environment naturally connected with the outside: 100 meters in length, by 50 wide, 60 deep. The stretch of caves accessible to the public is made up of very different environments in size and shape. Stalactites, stalagmites, curtains, columns, precious crystals peep out everywhere. The environments names are the fruit of the imagination of the early explorers: Wolf, Monuments, Owl, Madonnina, Altar, Precipice, Desert Corridor, Inverted Column, Red Hall, Dome. Finally, the last and most beautiful cave of the underground system, White Cave, defined for the wealth and whiteness of alabaster, the brightest in the world.