Located near Tochigi, Japan, Oya Stone Museum is a massive, former stone quarry that's now open to the public.
Largely developed during the Edo Period, these man-made caverns have been carved directly out of the durable, yet soft volcanic stone called Oya that is only local to this region. A small museum sits at the mine entrance that highlights the geology and history of the area, and showcases various mining tools that have been used throughout the centuries.
From here, guests can descend down into the massive underground halls to a space that is larger than the Tokyo dome. Filled with house art exhibits, these halls are brightly lit with colorful lights. They also include an all-stone stage and an all-stone chapel, as well as many other carved elements.