León Viejo is a World Heritage Site in Nicaragua. It was the original location of León. It is the present location of the town of Puerto Momotombo in the Municipality of La Paz Centro of the Department of León. It is is administered by the Instituto Nicaragüense de Cultura (Nicaraguan Institute of Culture). León Viejo was founded on June 15, 1524 by the Spanish conquistador, Francisco Hernández de Córdoba, who was decapitated in its Plaza Mayor (Major Plaza) in 1526 by Pedrarias Dávila, his Lieutenant.
This town, in other time inhabited for the first colonists after the discovery, in the beginning had in its suburbs a few 15.000 natural neighbors of the country. León Viejo is located on the banks of the Lago de Managua (Lake Managua or Lake Xolotlán), in front of the volcano Momotombo. The area suffered frequent volcanic activity, culminating in the earthquakes of 1594 and 1610. The city was not destroyed by the 1610 quake, however due to the damage it caused and due to the seismic characteristics of the place, its settlers held a popular consultation and decided to move the city to the present location of León, Nicaragua. The old city was gradually buried by the continuous expulsions of ash and volcanic stone and by lake sediments.
The ruins of León Viejo were discovered in 1967 and excavations begun the following year. The excavations revealed that the city had a similar layout to other cities in Latin America at that time, laid out in an exact square with a plaza located in its center. The center of León Viejo occupies an approximate area of 800 meters times 500 meters. Around the Plaza Mayor and on the border of the streets, 16 ruins have been partially restored. The city had three monasteries: "La Merced", "San Pedro" and "San Francisco", which remained active until 1560. The ruins of La Merced and San Pedro have been identified.
The ruins have been damaged by natural disasters over the years. In May, 1982 the tropical storm Alleta wasted the walls of the city. In October, 1988 the Hurricane Joan caused new damages to the ruins, and in October, 1998 the Hurricane Mitch caused damages affecting an estimated 40% of the site, affecting several houses, La Merced convent and La Fortaleza. León Viejo is the only colonial city from the 16th century settled in America that never suffered city-planning alterations during its history. This fact was the main argument in the request to the UNESCO when it was declared a World Heritage Site in 2000.