The most unusual feature of Wat Umong are these tunnels, which are built into an artificial mound in the forest. The legend goes that the temple and its tunnels were built in the late 14th century. On a level open space, a large artificial mound was built and then criss-crossed with tunnels. The story is that the temple was built like this for a highly regarded monk who was nonetheless a little crazy. The somewhat maze-like tunnels kept the mad monk from wandering off. The tunnel walls were once richly decorated, and it seems that plans are afoot to recreate the decorations if enough money can be raised.