of ; the (ball game court) with the or rack of skulls; the Sun Temple, which was dedicated to ; the Eagle's House, which was associated with warriors and the ancient power of rulers; the platforms for the gladiatorial sacrifice; and some minor temples. Outside was the palace of Moctezuma with 100 rooms, each with its own bath, for the lords and ambassadors of allies and conquered people. Also located nearby was the , or house of the songs, and the . The city had great symmetry. All constructions had to be approved by the , a functionary in charge of the city planning. Palaces of Moctezuma II The palace of Moctezuma II also had two houses or zoos, one for birds of prey and another for other birds, reptiles, and mammals. About 300 people were dedicated to the care of the animals. There was also a botanical garden and an aquarium. The aquarium had ten ponds of salt water and ten ponds of fresh water, containing various fish and aquatic birds. Places like this also existed in , , (now called Oaxtepec), and . Social classes Tenochtitlan can be considered the most complex society in Mesoamerica in regard to social stratification. The complex system involved many social classes. The were commoners who lived outside the island city of Tenochtitlan. The were noblemen who were relatives of leaders and former leaders, and lived in the confines of the island. , or eagle nobles, were commoners who impressed the nobles with their martial prowess, and were treated as nobles. were the highest class, rulers of various parts of the empire, including the king. were slaves or indentured servants. Finally, the were merchants who traveled all of Mesoamerica trading. The membership of this class was based on heredity. could become very rich because they did not pay taxes, but they had to sponsor the ritual feast of Xocotl Huetzi from the wealth that they obtained from their trade expeditions. Status was displayed by location and type of house where a person lived. Ordinary people lived in houses made of reeds plastered with mud and roofed with thatch. People who were better off had houses of adobe brick with flat roofs. The wealthy had houses of stone masonry with flat roofs. They most likely made up the house complexes that were arranged around the inner court. The higher officials in Tenochtitlan lived in