of General Luis Medina Barrón. From the 19th to the 23rd, General Medina used a light beacon brought from the port city of Veracruz to light the hills at night looking for rebel positions. The battle began at 10:00 a.m. on the 23rd with rebel cannon fire. Over 22,000 rebel troops then approached the city from four directions, from the mountains known as La Bufa, La Sierpe, Loreto and La Tierra Negra. The battle continued until about 5:00 that afternoon, when Huerta's troops began to abandon their positions, and the División del Norte took the strategic hills of La Bufa and El Grillo, entering the city. The rebels sacked the city and destroyed a number of buildings. Battle casualties were about 5,000 for Huerta's troops and about 3,000 for the rebels. After the Mexican Revolution, the city of Zacatecas decided to revive the original seal granted to it by Philip II, and make it the seal of both the city and the state. It had been discarded after the War of Independence. The "Marcha Aréchiga" or "Marcha Zacatecas" written by Genaro Codina in the early 20th century, became the semi official anthem of the city and state. 20th century The old Instituto de Ciencias was refounded as the Universidad Autónoma de Zacatecas in 1968, and an international airport was constructed in 1970. The anniversary of the city had been celebrated on the day of the Virgin of Zapopan, who was the patron until 1975. Since then the patron has been changed to the Virgin del Patrocinio, who is celebrated on the same day,. The city center was named a World Heritage Site in 1993. UNESCO's websites states the following as justification. "Founded in 1546 after the discovery of a rich silver lode, Zacatecas reached the height of its prosperity in the 16th and 17th centuries. Built on the steep slopes of a narrow valley, the town has views of the area. There are also several old buildings, both religious and civil. The cathedral, built between 1730 and 1760, dominates downtown. It is notable for its harmonious design and the Baroque profusion of its façades, where European and indigenous decorative elements are found side by side." Zacatecas has had a number of earthquakes since the colonial period. The last occurred in 1995 and caused minor damage. 21st century In 2009, the city council approved the logotype of the new administration with