Fujido Cave, located in Gunma prefecture, is the largest limestone cave in the Kanto region of Japan. With a grand length of 2.2 kilometers (1.3 miles), a walk from one end to the other is expected to take 40 minutes. Needless to say, there's plenty of exploration to be done. Having been explored for over 400 years, you'll find much of the cave system has managed to accrue various titles over the years by explorers with a sharp naming sense. Alongside all of the Buddhist names, walk with pride past "Woman's Change-room" or "Lotus Tower". A great deal of fun to explore and learn about, see if you can't come up with a creative name for a stalactite you pass by.