Eisriesenwelt is the largest ice cave in the world located near Werfen, in the Austrian state of Salzburg. It is a natural wonder and attracts many tourists every year. Eisriesenwelt literally means "World of the Ice Giants," and it is an extensive cave system that extends more than 40 kilometers, of which only about 1 km is open to the public.

The cave system was formed by natural processes over millions of years, and it contains a labyrinth of winding passages, icy chambers, and stunning ice formations. The ice inside the cave is said to be more than 1,000 years old and is still growing in some parts.

The cave's entrance is at an altitude of 1,675 meters, and visitors must climb a steep path to reach the entrance. The cave is open to visitors from May to October, and guided tours are available. Visitors are advised to wear warm clothing, as the temperature inside the cave is constantly below freezing.

In addition to its natural beauty, the Eisriesenwelt has an interesting history. It was first discovered in 1879 by Anton Posselt, and it was later explored by numerous scientists and explorers. During World War II, the cave was used as a secret storage facility for art treasures, and it was also used as a setting for the filming of several movies. Today, it is a popular tourist attraction and a must-visit destination for anyone traveling to Austria.