Located in the highest part of the site, which demonstrates its hierarchical importance, where the nobles and highest-ranking people of the city lived. In this space are The Acropolis, the Temple of the Feathered Serpents, the Twin Pyramid and the Temple of the Steles.

Acropolis: Architectural complex that was made up of eight structures with patios surrounded by rooms. In this place, the sculpture known as “Lord in Red” was found, made of volcanic stone carved in two sections, measuring 2 m high, 85 cm wide and 10 cm thick. It is coated with abundant cinnabar powder which gives it the red color that can be seen nowadays. It has the shape of a person, whose head was represented by a circle of feathers, while its arms and legs were made in the likeness of corn plants, with decorations of sacred beads, the figure seems to be sitting on the Ollin symbol that represents the movement. Due to the place where it was found, it is thought that it marked exactly the central part of the Acropolis and the highest point of Xochicalco hill. Serving as the main axis for the layout of the city. The piece is on permanent display inside Room 2 of the Site Museum.

Twin Pyramid: It is called this way because it has the same shape and dimensions as the Temple of the Feathered Serpents. It is possible that it could have been built because at some point in the Xochicalco history, two people ruled at the same time, that is why its characteristics are similar; only unlike the Temple of the Feathered Serpents, this one was decorated with paintings of several motifs on all its facades.

Structures 6 and 7: They close the Main Plaza on the east side, and have numerous rooms around patios. Access to Structure 6 is through two porticos; however, the main entrance is behind and in the center of the Temple of the Feathered Serpents. Inside one of the rooms of this structure, was found an altar, where apparently there was a sculpture of a snake head with its jaws open, from which the head of an individual emerged.

Moreover, Structure 7 was partially destroyed by the inhabitants of Xochicalco. Only a patio can be seen three rooms, and a large hall with a section of mural painting with geometric and anthropomorphic representations was rescued. These structures show an administrative use in the heart of the city.