The gates carry a date that explains everything: the project was signed into law on December 6, 1896, decades after the disaster that prompted it. Mendoza's 1861 earthquake had killed thousands and left the survivors exposed to disease, and the city's Minister of Works, Emilio Civit, folded a great park into a larger plan for reforestation and flood control. Not everyone approved. Opposition politicians called it an elitist indulgence, arguing the money would be better spent on sewers and irrigation ditches the city still lacked. They had a point. But the park endured, and over time it did exactly what its defenders promised, lifting air quality, property values, and the simple daily comfort of a population living at the edge of the Andean desert.

The man hired to design it was Carlos Thays, a French-born landscape architect who had already reshaped green Argentina from Buenos Aires outward. Thays mixed English and French nineteenth-century styles, threading wide avenues and curving paths through ground that had to be irrigated into life. He understood this work; his other commissions included Buenos Aires's vast Parque Tres de Febrero and the bones of what became Nahuel Huapi National Park. In Mendoza he gave the city a stage set of imported trees, fountains, and sculpture. Originally called the Parque del Oeste, the Western Park, it was later renamed for General José de San Martín, the liberator whose Army of the Andes had assembled in this very region before crossing the mountains to free Chile and Peru.

Wander the grounds and you stop thinking of it as a park at all. Thirty-four sculptures punctuate the roads. The grand main gates, installed in 1909, are crowned with a condor and carry the coat of arms of the city, an iron threshold between the dust of Mendoza and the green beyond. The rose garden, El Rosedal, has bloomed along its promenade since 1919, and a lake inaugurated in 1906 still carries the rowing shells of a club founded in 1909. Crowded into the green are the Universidad Nacional de Cuyo, a zoo, a botanical garden, a hippodrome, a velodrome, a tennis club, the Estadio Malvinas Argentinas, and the Monument to the Army of the Andes, sculpted by Juan Manuel Ferrari and unveiled in 1914. Tucked among them, the Cornelio Moyano Museum of Anthropology and Natural Sciences guards some forty thousand objects. The park is less a garden than a small civic world, with the dry mountains always visible just beyond the leaves.

Every year the park becomes the heart of Mendoza's defining celebration. Since 1963 the Frank Romero Day Amphitheater has hosted the Fiesta Nacional de la Vendimia, the national grape harvest festival — an event that dates to 1936 but found its permanent home here when the great open-air theater opened — when the wine country that surrounds the city pours into the hills above the lake to crown a harvest queen under stage lights and fireworks. It is a fitting role. This is a place built on the idea that water and labor can turn desert into abundance, and the festival celebrates the same alchemy in liquid form. The greenery that Thays conjured and the vineyards that made Mendoza famous spring from the same stubborn faith in irrigation. To climb the wooded slope to the Cerro de la Gloria at the park's edge, where the Army of the Andes monument stands, is to see it all laid out at once: the green canopy below, the grid of the city beyond, and the snow on the Andes closing the horizon. At sunset, with the peaks gone gold, the whole improbable achievement comes into focus.