had a strong presence in the city, and were settled in two main areas of the island, designated San Juan Tenochtitlan and Santiago Tlatelolco, each with a municipal council that functioned the entire colonial period. San Juan Tenochtitlan was a Spanish administrative creation, which amalgamated four indigenous sections, with each losing territory to the Spanish . The Spanish laid out the streets of the in a checker board pattern, with straight streets and plazas at intervals, whereas the indigenous portions of the city were irregular in layout and built of modest materials. In the colonial period both San Juan Tenochtitlan and Santiago Tlatelolco retained jurisdiction over settlements on the mainland that they could draw on for labor and tribute demanded by the Spanish, but increasingly those subordinate settlements () were able to gain their autonomy with their own rulers and separate relationship with the Spanish rulers. Concern about the health of the indigenous population in early post-conquest Mexico–Tenochtitlan led to the founding of a royal hospital for indigenous residents. There are a number of colonial-era pictorial manuscripts dealing with Tenochtitlan–Tlatelolco, which shed light on litigation between Spaniards and indigenous over property. An account with information about the war of Tenochtitlan against its neighbor Tlatelolco in 1473 and the Spanish conquest in 1521 is the . Anthropologist Susan Kellogg has studied colonial-era inheritance patterns of Nahuas in Mexico City, using Nahuatl- and Spanish-language testaments. Ruins Tenochtitlan's main temple complex, the Templo Mayor, was dismantled and the central district of the Spanish colonial city was constructed on top of it. The great temple was destroyed by the Spanish during the construction of a cathedral. The location of the Templo Mayor was rediscovered in the early 20th century, but major excavations did not take place until 1978–1982, after utility workers came across a massive stone disc depicting the nude dismembered body of the moon goddess Coyolxauhqui. The disc is in diameter, and is held at the Templo Mayor Museum. The ruins, constructed over seven periods, were built on top of each other. The resulting weight of the structures caused them to sink into the sediment of Lake Texcoco; the ruins now rest at an angle instead of horizontally. Mexico City's Zócalo, the Plaza de la Constitución, is located at the site of Tenochtitlan's original central plaza and market, and many of the original calzadas still correspond to modern city streets. The Aztec calendar