Alegria died at the Cardiovascular Center of Puerto Rico and the Caribbean from complications of heart disease, said his son, Ricardo Alegria Pons. The elder Alegria had been treated for two weeks at the hospital in June and then was hospitalized again Sunday.
"Thanks to his long life of 90 years, he has had a major impact on all aspects of the culture of all Puerto Ricans," his son told reporters. "That work and dedication and love of his country does not disappear with his death."
Gov. Luis Fortuno declared five days of mourning in the U.S. territory, ordering American and Puerto Rican flags to be lowered to half-staff in honor of one of the island's leading cultural figures.
Alegria in 1955 helped found and later served as executive director of the Institute of Puerto Rican Culture, where he was long a passionate advocate of preserving the island's artistic and archaeological heritage. He went on to launch the Graduate Center for Advanced Studies on Puerto Rico and the Caribbean in 1976 and received the United Nations Educational, Scientific and Cultural Organization's Picasso Medal in 1993.
Born April 14, 1921, Alegria earning a master's degree in anthropology and history at the University of Chicago and a doctorate in anthropology at Harvard University.
Source: Associated Press