Puerta de Tierra is a subbarrio (subdistrict) occupying the eastern portion of the Islet of San Juan and the barrio of San Juan Antiguo in the municipality of San Juan, Puerto Rico. The name Puerta de Tierra derives from the former eastern gated entrance to the walled city of San Juan where Plaza Colón is today. With a population of 2,924 as of 2010, this is the most populated area of San Juan Antiguo. On October 15, 2019, it was added to the National Register of Historic Places.

San Juan Islet is a 3-square-mile (7.8 km2) islet or small island on San Juan Bay in the Atlantic coast of northern Puerto Rico. Home to Old San Juan, it is the site of the oldest permanent European settlement in Puerto Rico (1521), and the second oldest European settlement in the West Indies after Santo Domingo (1496). Due to its strategic location in the Caribbean during the Spanish colonization of the Americas, it is home to a city wall and a number of militaristic buildings such as El Morro Castle. Today, it is also home to many of Puerto Rico's government buildings such as the territory's capitol building.