It has five naves consisting of 51 vaults, 74 arches and 40 columns. The two bell towers contain 25 bells. The tabernacle, adjacent to the cathedral, contains the baptistery and serves to register the parishioners. There are five large, ornate altars, a sacristy, a choir, a choir area, a corridor and a capitulary room. Fourteen of the cathedral's sixteen chapels are open to the public. Each chapel is dedicated to a different saint or saints, and each was sponsored by a religious guild. The chapels contain ornate altars, altarpieces, retablos, paintings, furniture and sculptures. The cathedral is home to two of the largest 18th-century organs in the Americas. There is a crypt underneath the cathedral that holds the remains of many former archbishops. The cathedral has approximately 150 windows. Over the centuries, the cathedral has suffered damage. A fire in 1967 destroyed a significant part of the cathedral's interior. The restoration work that followed uncovered a number of important documents and artwork that had previously been hidden. Although a solid foundation was built for the cathedral, the soft clay soil it is built on has been a threat to its structural integrity. Dropping water tables and accelerated sinking caused the structure to be added to the World Monuments Fund list of the 100 Most Endangered Sites. Restoration working beginning in the 1990s stabilized the cathedral and it was removed from the endangered list in 2000. History Background: The Major Church After the Spanish conquest of the Aztec Empire, and after Hernán Cortés returned from exploring what is today Honduras, the conquistadors decided to build a church on the site of the Templo Mayor of the Aztec City of Tenochtitlan in order to consolidate Spanish power over the newly conquered territory. There is evidence of the existence of a great major temple dedicated to the god Quetzalcoatl, a temple dedicated to the god Huītzilōpōchtli and other minor buildings. The architect Martín de Sepúlveda was the first director of the project between 1524 and 1532, while Juan de Zumárraga was the first bishop of the episcopal see in the New World. The cathedral of Zumárraga was located in the northeastern part of what is now the cathedral. It had three naves separated by Tuscan columns, the central ceiling had intricate engravings made by Juan Salcedo Espinosa and gilded by Francisco de Zumaya and Andrés de la Concha. The main door was probably