Inaugurated in 1894 to occupy a whole block of the Balvanera district along Córdoba Avenue, the building was designed around twelve enormous water tanks stacked across three floors, with a combined capacity of 72,000 tons. Everything decorative was, in a sense, a disguise for that purpose. It replaced an earlier and frankly ugly water tower on Lorea Plaza, near where Congress now stands, and the planners decided that if a reservoir had to sit in the middle of the growing capital, it might as well be magnificent. The water tanks are long gone, dismantled in 1978, but the iron skeleton that once held all that weight remains, and the palace still functions in part as a working pumping station for the city it has served for well over a century.

The skin is the spectacle. More than 300,000 glazed, multicolored terracotta tiles cover the exterior, every one of them manufactured by Royal Doulton in Britain and shipped across the Atlantic to be fitted into place. The supporting iron structure came from Belgium, and the whole composition rests on 180 columns, an international collaboration assembled into a single ornate whole. Set into the facade are escutcheons representing the fourteen Argentine provinces that existed at the time, so the building wears the map of its own country across its walls. The effect at street level is overwhelming, a riot of pattern and color that stops pedestrians mid-stride, most of whom never guess that all this finery was wrapped around millions of liters of water. The building belonged to a British-owned water company until Argentina nationalized that company in 1892 and the palace passed to the city, a small monument to the era when British capital and British craftsmanship built much of modern Buenos Aires.

The palace guards something less visible but just as remarkable: the archives of how Buenos Aires was built and watered. Established in 1873, these are the only records that hold complete information on the city's water and sanitation planning. One collection contains plumbing and fire-hydrant plans for some 320,000 lots, the oldest dating to 1889, an archive so vast it numbers in the millions of documents. Among them are the plans of buildings that no longer exist, demolished to carve out the great avenues, including the colossal 9 de Julio. There are records of nearly every structure ever connected to the water network, building by building, owner by owner. It is, in effect, the paper memory of an entire metropolis.

Today the building has settled into a quieter life. It houses offices of Agua y Saneamientos Argentinos, the company that now runs the city's water, alongside the historic archives and a small museum dedicated to the waterworks. Inside, visitors can see surviving pipes and the original ceramics, the inner workings of a system that once defined modern, sanitary Buenos Aires when clean water was still a hard-won achievement. The palace even reached into literature: it figures prominently in Tomás Eloy Martínez's celebrated novel Santa Evita, woven into one of Argentina's most haunting fictions about the wandering corpse of Eva Perón. A water tank that became a palace, and then became a legend.