This impressive multi-roomed building is located at the northern end of the settlement axis. It was built over several periods. The Maya succeeded in giving it symmetry by reproducing the porticoes, entrances, false corridors, small columns and masks with serpentine motifs (the latter are on the second level). This solution is considered to be a true architectural design masterpiece. The columns are the star element of the entire building. They are not only present in the porticoes; they are also found in the form of reeds throughout the building.