León Viejo city was one of the first urban centers in the new world, and is the only one in Latin America that retains its original design. Similarly, in terms of rank and hierarchy, it was the main of the entire territory, having been the seat of the Provincial Colonial Government, custody of the Royal Fund, seat of the Province’s Diocese, and seat of the Cathedral of Santa María de la Gracia. This city is a living example of town planning and architecture of the sixteenth century. The ruins and their vestiges were originally discovered in 1931, and re-discovered in 1967 by researchers from the National Autonomous University of Nicaragua (UNAN-León) with clear public interest, and excavations begun the following year in search of historical vestiges. The excavations revealed that the city had a similar layout to almost all the cities of Hispanic America at that time, laid out on a grid system, with a main square located at its center.