Historians believe the park's eastern barranca to have been the site of Spanish Conquistador Pedro de Mendoza's landing on what became the first, failed attempt to establish Buenos Aires in 1536. Well to the south of the colonial hamlet, the land was first purchased by Manuel Gallego y Valcárcel around 1790. The lot was later purchased by a succession of English Argentines, the last of whom, Charles Ridgley Horne, improved and expanded the property, raising a baroque mansion on the land's western edge, Defensa Street. Allied to the repressive paramount Governor of Buenos Aires, Juan Manuel de Rosas, Ridgley Horne was forced into exile after the strongman's 1852 overthrow, however, and the land was sold to José Gregorio Lezama, who added adjoining lots to the north and gave the green space its current dimensions.