| Fortress of the Immaculate Conception | |
|---|---|
El Castillo de la Inmaculada Concepción | |
| El Castillo, Río San Juan Department, Nicaragua | |
 Fortress of the Immaculate Conception | |
  Fortress of the Immaculate Conception Location of the Fortress of the Immaculate Conception within Nicaragua | |
| Coordinates | 11°01′09″N 84°23′47″W / 11.0192°N 84.3964°W |
| Type | Bastion, Fortress |
| Site information | |
| Controlled by | Nicaragua |
| Open to the public | Yes |
| Site history | |
| Built | 1673–1675 |
| Built by | Martín de Andújar Cantos |
| In use | 1675–present |
| Materials | Stone |
| Battles/wars | Battle for the Río San Juan de Nicaragua (1762) San Juan Expedition (1780) |
| Garrison information | |
| Past commanders | Lieutenant Colonel Don José de Herrera y Sotomayor (1762)[1] |
The Fortress of the Immaculate Conception, (Spanish: El Castillo de la Inmaculada Concepción) is a fortification located on the southern bank of the San Juan River (Río San Juan), in the village of El Castillo in southern Nicaragua. The fortress is situated approximately 6 kilometers from the border with Costa Rica, at the Raudal del Diablo rapids of the San Juan River. It was completed in 1675 as part of a series of fortifications along the San Juan River, to defend against pirate attacks upon the city of Granada (which can be reached by navigating upstream from the Caribbean Sea along the San Juan River into Lake Nicaragua). The settlement of El Castillo and its fortress continued to be strategically important to the Captaincy General of Guatemala until the late 18th century.
An important historic landmark of Nicaragua, the fortress is on a list of sites as an initial stage in achieving World Heritage Site status with the United Nations Educational, Scientific and Cultural Organization (UNESCO).