Question: What was the capital city of the aztec empire?

Disambiguated questions and answers:
context: The Spaniards and their allies, realizing they were vulnerable to the hostile Mexica in Tenochtitlan following Moctezuma's death, attempted to retreat without detection in what is known as the "Sad Night" or La Noche Triste. Spaniards and their Indian allies were discovered clandestinely retreating, and then were forced to fight their way out of the city, with heavy loss of life. Some Spaniards lost their lives by drowning, loaded down with gold. They retreated to Tlacopan (now Tacuba) and made their way to Tlaxcala, where they recovered and prepared for the second, successful assault on Tenochtitlan. After this incident, a smallpox outbreak hit Tenochtitlan. As the indigenous of the New World had no previous exposure to smallpox, this outbreak alone killed more than 50% of the region's population, including the emperor, Cuitlahuac. While the new emperor Cuauhtémoc dealt with the smallpox outbreak, Cortés raised an army of Tlaxcalans, Texcocans, Totonacs, and others discontent with Aztec rule. With a combined army of up to 100,000 warriors, the overwhelming majority of which were indigenous rather than Spanish, Cortés marched back into the Basin of Mexico. Through numerous subsequent battles and skirmishes, he captured the various indigenous city-states or altepetl around the lake shore and surrounding mountains, including the other capitals of the Triple Alliance, Tlacopan and Texcoco. Texcoco in fact had already become firm allies of the Spaniards and the city-state, and subsequently petitioned the Spanish crown for recognition of their services in the conquest, just as Tlaxcala had done.
question: What were the capital cities of the aztec empire initially?
short_answers: Tlacopan

Texcoco

Tenochtitlan
wikipage: Aztec Empire

context: Traditionally, provinces and altepetl were governed by hereditary tlatoani. As the empire grew, the system evolved further and some tlatoani were replaced by other officials. The other officials had similar authority to tlatoani. As has already been mentioned, directly appointed stewards (singular "calpixqui", plural "calpixque") were sometimes imposed on altepetl instead of the selection of provincial nobility to the same position of tlatoani. At the height of empire, the organization of the state into tributary and strategic provinces saw an elaboration of this system. The 38 tributary provinces fell under the supervision of high stewards, or "huecalpixque", whose authority extended over the lower-ranking calpixque. These calpixque and huecalpixque were essentially managers of the provincial tribute system which was overseen and coordinated in the paramount capital of Tenochtitlan not by the "huetlatoani", but rather by a separate position altogether: the "petlacalcatl". On the occasion that a recently conquered altepetl was seen as particularly restive, a military governor, or "cuauhtlatoani", was placed at the head of provincial supervision. During the reign of Moctezuma I, the calpixque system was elaborated, with two calpixque assigned per tributary province. One was stationed in the province itself, perhaps for supervising the collection of tribute, and the other in Tenochtitlan, perhaps for supervising storage of tribute. Tribute was drawn from commoners, the "macehualtin", and distributed to the nobility, be they 'kings' ("tlatoque"), lesser rulers ("teteuctin"), or provincial nobility ("pipiltin").
question: What was the most important capital city of the aztec empire?
short_answers: Tenochtitlan
wikipage: Aztec Empire

Long answers:
knowledge: content: The Aztec Empire, or the Triple Alliance (Classical Nahuatl: Ēxcān Tlahtōlōyān, [ˈjéːʃkaːn̥ t͡ɬaʔtoːˈlóːjaːn̥]), was an alliance of three Nahua altepetl city-states: Mexico-Tenochtitlan, Tetzcoco, and Tlacopan. These three city-states ruled that area in and around the Valley of Mexico from 1428 until the combined forces of the Spanish conquistadores and their native allies under Hernán Cortés defeated them in 1521.
wikipage: Aztec Empire

content:  Despite the initial conception of the empire as an alliance of three self-governed city-states, Tenochtitlan quickly became dominant militarily.[4] By the time the Spanish arrived in 1519, the lands of the Alliance were effectively ruled from Tenochtitlan, while the other partners in the alliance had taken subsidiary roles.
wikipage: Aztec Empire
long_answer: Initially, The Aztec Empire had an alliance of three self-governed city-states including Mexico-Tenochtitlan, Tetzcoco, and Tlacopan, also known as the Triple Alliance. The Triple Alliance ruled the area in and around the Valley of Mexico. Despite the initial conception of the Triple Alliance, Tenochtitlan quickly became dominant militarily by the time the Spanish arrived in 1519.