El Zanjón de Granados: the colonial tunnels beneath a San Telmo house, Buenos Aires

In San Telmo, at number 755 of calle Defensa, there is a house that from the outside looks like one of the neighbourhood's many middle-class homes. In 1985 Jorge Eckstein bought it, abandoned and full of rubble, meaning to open a restaurant there. During the clearing work the floor gave way and beneath it appeared something no one had expected: a brick structure buried for over a century. Eckstein changed his plans, and what had been a building site became an archaeological dig lasting years. Today El Zanjón de Granados is considered the most important archaeological site in the city.

Beneath the house

Beneath mounds of rubbish and debris, first a house from 1830 came to light, built for a wealthy Spanish family of leather merchants, then — deeper down — the oldest storm-drainage system in Buenos Aires. Right there ran the Arroyo Tercero del Sur, the watercourse that marked the southern boundary of the city founded by Juan de Garay in 1580. The word "zanjón" means precisely a large ditch. The property lived through every phase of the neighbourhood: a grand residence abandoned after the yellow fever epidemic that struck the south of the city, then a conventillo where dozens of poor families crowded in, and finally a ruin shut up for decades.

The tunnels

The underground part is the most astonishing. The tunnels rise more than three metres high, with brick vaults eroded by water; floors, walls and part of the roofing are original. Each family, back then, built its own stretch of drainage channel beneath its lot, and this piecemeal logic can still be read in the joints of the masonry. A technical curiosity: you can pass underground from the building on calle Defensa to the one on calle Chile thanks to a right of way, a legal arrangement first applied in Buenos Aires right here. Legends are not lacking — the guides tell of noises and presences sensed by visitors — but the real spectacle is the tangible stratification of over four centuries of city, legible to the naked eye.

The visit

It can be visited only with a guided tour, at scheduled times and in groups of at most twenty people. This, more than its low profile, is what keeps El Zanjón out of the tourist flow that overruns the nearby attractions: the famous Plaza Dorrego with its Sunday market and the Mercado de San Telmo are a few blocks away, always crowded, whereas here you enter in staggered groups and by reservation. Two distinct routes are offered: "El Zanjón - Túneles y Misterio", of about 50 minutes, and "Casa Mínima", of about 40. Entry is from Defensa 755, the exit from calle Chile 450. Visits are concentrated between 11 a.m. and 5 p.m.; on weekends and holidays the timings are more numerous. It is best to book ahead (tickets are bought online) and to check times and prices on the official site, since they change with the season.

Getting there

To get there: San Telmo is just south of the centre, reachable on foot from Plaza de Mayo in about ten minutes. The most convenient metro station is the line C stop at Plaza Constitución or, alternatively, the stops around Plaza de Mayo, from which you head down calle Defensa. A practical tip: pair the visit with a stroll around the neighbourhood at hours when the tour is not running, so you see San Telmo before it fills up. Contact and reservations through the site elzanjon.com.ar.

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