The fourth temple was constructed between 1440 and 1481 during the reigns of Moctezuma I and Axayacatl. This stage is considered to have the richest of the architectural decorations as well as sculptures. Most offerings from the excavations are from this time. The great platform was decorated with serpents and braziers, some of which are in the form of monkeys and some in the form of Tlaloc. At this time, the stairway to the shrine of Tlaloc was defined by a pair of undulating serpents and in the middle of this shrine was a small altar defined by a pair of sculpted frogs. The circular monolith of Coyolxauhqui also dates from this time.