The House of Chultun (Mayan for Cistern). Beyond the columns at the entrance; is a large closed area with a small sanctuary, and a room that was added at a later date. The roof of the structure, now gone, was flat and built on wood beams covered inside-out with lime concrete. Over the main and secondary doorways were niches with the stucco figures of the descending god, seen in most buildings at Tulum. The walls inside were painted with mythological figures; black and red color remains were found in it. A chultun is a deposit for rain water and this structure receives its name due to the chultun found in its premises.