Wat Si Chum (Thai: วัดศรีชุม) has a massive mandapa in the middle of the complex which was built in the late 14th century by King Maha Thammaracha II. Inside the mandapa, there is a huge 11 meters wide and 15 meters high seated Buddha image called "Phra Achana", which was mentioned in Ramkhamhaeng stele. The Mandapa has a square base of 32 meters on each side and 15 meters high, and its walls are three feet thick. In the south wall there is a narrow staircase passage which can be used to reach the roof. In this passage more than 50 slates were discovered on which images from the life of Buddha (Jataka) are engraved. These slates are the oldest surviving examples of Thai art of drawing. East of mandapa are the ruins of vihara with column fragments and three Buddha image pedestals. North of the Mandapa are the ruins of another small vihara and another smaller mandapa with a Buddha image. The entire complex is surrounded by a moat. There is a legend that to boost morale of the ancient soldiers and people, the kings went through the hidden passageway and address the people through a hole, making them believed the voice they were hearing was actually the Buddha's.