Introduction to stalactites: The cave is full of colorful stalactites, stone flowers, stalagmites, stone pillars, and stone terraces of different shapes. There are also magical underground rivers, waterfalls, and geysers. The entrance is not far away. There is also a huge cave hall. The hall is more than 60 meters high, which is equivalent to a twenty- to thirty-story building. The ground diameter of the hall is more than 100 meters, and a football field can be placed inside. What's particularly mysterious is that any sound that is made in the hall is immediately diffused into a beautiful, melodious music that echoes throughout the cave for a long time. Some people call it the "Golden Hall" of Vienna.