Carnegie Library, Carnegie library in Puerta de Tierra, San Juan, Puerto Rico

The Biblioteca Carnegie on Avenida Juan Ponce de León in Puerta de Tierra, San Juan, is a Classical Revival building designed and built by Puerto Rican engineer Ramón Carbia, with work starting in 1914 on land donated by the Puerto Rico government. Completed in 1915, it was Puerto Rico's first purpose-built library, funded by a $100,000 Carnegie Foundation donation. Its first forty years saw nine reading rooms, a membership system and about 200 visitors a day.

Education commissioner Martin Grove Brumbaugh began talks with Andrew Carnegie in 1901, and the San Juan legislature pledged $6,000 for upkeep; Carnegie gave $100,000. Engineer Ramón Carbia designed the Classical Revival building, completed in 1915 on land donated by the Puerto Rico government. The Insular Library collection moved in during June 1916, and the library was inaugurated on 27 July 1916.

The library's name comes from Andrew Carnegie, whose foundation gave $100,000, and its 1916 opening was marked by the transfer of the Insular Library collection. From 1969 it hosted the Salón de Humoristas de Puerto Rico for 22 years, showing cartoonists such as Carmelo Filardi and Ramón Arroyo Cisneros; Luis Muñoz Marín wrote that "Humor is intelligent laughter." In 1973 it held the first meetings of the UNESCO Cultural Center and 36 UNESCO chamber music concerts, with Jesús María Sanromá and Héctor Campos Parsi.

The library stands on Avenida Juan Ponce de León in Puerta de Tierra, a short walk from the waterfront and from the Ateneo Puertorriqueño next door. It has been closed since Hurricane Hugo damaged the building in 1989, and later community efforts to reopen it failed, so check locally before planning a visit. The San Juan municipal legislature accepted the building, its possessions and its land from the Department of Education in 2010.

The library's 1948 Biblioteca Rodante sent two vehicles with cajas viajeras, travelling boxes of books, to isolated schools and communities, serving readers from elementary pupils to adults in their eighties and nineties.