San Juan de Nicaragua, formerly known as San Juan del Norte or Greytown, is a town and municipality in the Río San Juan Department of Nicaragua. San Juan del Norte was founded by the Spanish and was a small fort and customs station. Spanish explorers first reached the bay at the mouth of the San Juan River on 24 June 1539 and named it San Juan del Norte. A garrison was first established in 1541 as San Juan de la Cruz by Nicaraguan governor Rodrigo Contreras.