2,500 people, the largest single population center is the town of San Miguel de Allende, which houses 59,691 people, about 44% of the municipality's population. The next three largest towns each have populations smaller than 3,000 people: Los Rodríguez (2,768), Colonia San Luis Rey (1,850), and Corral de Piedras de Arriba (1,701). These smaller communities are populated by the municipality's indigenous groups, mostly Otomi and Nahuas. The Otomi are the largest group, accounting for just under 38% of the municipal population. The Nahuas follow at about 20%. Other groups include the Mazahua, Huasteca and Purépecha. However, according to the 2002 census, only 520 people speak an indigenous language, 472 of whom also speak Spanish. Catholicism is practised by 96% of the population, with most others being Protestants, among them Evangelicals. The municipality is home to three institutions of higher education, the Instituto Tecnológico SSC, a campus of the Universidad Tecnólogica de León, and the Universidad Tecnológica de San Miguel de Allende. The city also has bilingual schools that follow the curriculum of the American educational system. As of 2000, 17.5% of the population is considered to be illiterate, compared to 12.1% for the rest of the state. Landmarks Historic core zone The historic core zone of San Miguel was defined by the federal government in 1982 and adopted by UNESCO in 2008. This is a 43 hectare area, partly defined by Insurgentes to the north, Quebrada to the west, and Terraplen and Huerta to the south. Two buffer zones totaling about forty hectares are adjacent to the core zone. At the entrance of the city stand the statues of Ignacio Allende, Juan Aldama, Miguel Hidalgo and Josefa Ortiz de Dominguez, with one of the Archangel Michael in the center. While the outlying areas of the town and municipality have changed over time, the historic center remains much as it was 250 years ago. The layout of the center of the city is mostly a straight grid, as was favored by the Spanish during colonial times. However, due to the terrain, many roads are not straight. There are no parking meters, no traffic signals and no fast food restaurants. These roads are lined with colonial-era homes and churches. With a few exceptions, the architecture is domestic rather than monumental, with well-tended courtyards and rich architectural details. The houses have solid walls against the sidewalks, painted in various colors, many with bougainvillea