San Germán (Spanish pronunciation: [saŋ xeɾˈman]) is a municipality located in the southwestern region of Puerto Rico, south of Mayagüez and Maricao, north of Lajas, east of Hormigueros and Cabo Rojo, and west of Sabana Grande. San Germán is spread over eighteen barrios plus San Germán Pueblo (the downtown area and the administrative center of the city). It is both a principal city of the San Germán–Cabo Rojo Metropolitan Statistical Area and the Mayagüez–San Germán–Cabo Rojo Combined Statistical Area. San Germán is the second oldest city of Puerto Rico, after San Juan. The island of Puerto Rico was once split between the San Juan and the San Germán municipalities. The latter covered the western half of Puerto Rico, and extended from the western shores of the island to Arecibo in the north and Ponce in the south.
The population of San Germán when Alonso Manso was named the first bishop of Puerto Rico in 1511 was "about 50 neighbors".
Spanish settlement in San Germán occurred early in the conquest and colonization of Puerto Rico. After the destruction of a small early settlement near modern-day Añasco during a Taíno uprising which started in February 1511, in 1512 the new settlement was built by Miguel Diaz at Guayanilla and named after Germaine of Foix, the new queen of King Fernando. This town was attacked by French corsairs in August 1528, May 1538 and 1554. The construction of a small fort began in 1540, but work stopped in 1546 when the population of the town began moving inland to the current modern location.
An early written reference to the new town occurs in 1573.