Construction began on 1924 and first classes were held on July 2, 1927. The faculties of Philosophy and Letters, Liberal Arts (they would later merge under the Philosophy and Letters name, later to be renamed as the
Faculty of Arts and Letters), Faculties of
Medicine and
Pharmacy,
Faculty of Engineering, and the
College of Education were the first occupants who transferred to the new building. Since then, the Main Building has been the focal point of the campus. It is where all succeeding structures revolved. After the
invasion and
occupation of the Philippines by the Japanese during
World War II, the Japanese converted the university into the
Santo Tomas Internment Camp for Americans and other non-Filipinos starting on January 4, 1942. Three floors of the building were occupied by the internees. Several internees were located in the Education Building (now housing the
University of Santo Tomas Hospital) and other buildings. On February 3, 1945, during the
Battle for Manila the university was liberated by the
1st Cavalry Division, tanks from the 44th Tank Battalion and Filipino guerrillas. On February 4, Japanese commander
Toshio Hayashi took some of the internees hostage in the nearby Education Building and negotiated for the Japanese soldiers to rejoin Japanese forces in the south of the city in exchange for the internees. A plaque dedicated in 1954 commemorates the event. After the war, UST resumed operation, holding classes in the building. The university and the building was visited by
Pope Paul VI in 1970 and
Pope John Paul II in 1995 when UST hosted
World Youth Day 1995. In 2015,
Pope Francis became the third pope to visit the university, but did not enter the building. Aside from Popes, several notable international figures have visited the building. In 2012,
Queen Sofia of Spain visited the building. ==Gallery==