The Cathedral Basilica of St. Augustine is a historic cathedral in St. Augustine, Florida, and the seat of the Catholic Bishop of St. Augustine. It is located at 38 Cathedral Place between Charlotte and St. George Streets. Constructed over five years (1793–1797), it was designated a U.S. National Historic Landmark on April 15, 1970. Its congregation, established in 1565, is the oldest Christian congregation in the contiguous United States.

The Diocese of St. Augustine is a Latin Church ecclesiastical territory of the Catholic Church, located in the northeastern section of Florida in the United States. It includes the cities of St. Augustine, Jacksonville, and Gainesville.