A true hidden gem in Buenos Aires lies beneath the surface: the mysterious underground tunnels of El Zanjón de Granados in San Telmo. This unique site offers a fascinating glimpse into the city’s past and its evolution over the centuries, all brought to life through a professionally guided tour. In this article, I’ll explain why visiting El Zanjón de Granados is an unforgettable experience and provide details on when you can plan your visit.
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Underground tunnels in Buenos Aires
A little bit of history
In the 16th century, open creeks crisscrossed the area of San Telmo, providing water and shaping the landscape for the early settlers. As the city expanded, these waterways were gradually enclosed. By the late 19th century, most of the creeks had been integrated into an underground sewer system, disappearing beneath the growing urban sprawl.
El Zanjón de Granados construction was finalized in 1830 by Marcos Miguens, one of Buenos Aires’ upper-class elites. The family moved from Galicia – Spain to Argentina in 1767. However, the construction had some issues in 1787 due to heavy rains and overflooding of the area. After that event, it was decided to build underwater waterways to give the river it way to pass the city.
But then yellow fever hit in the 1870s, and everything changed. Like most wealthy families in San Telmo, the owners packed up and moved north to neighborhoods like Recoleta to escape the epidemic. At that time it was rural areas outside Buenos Aires center. The once-grand home fell into decline and eventually became conventillo (tenement house), cramming multiple immigrant families – sometimes over more than 100 people – into small, shared spaces during Buenos Aires’ population boom.
This shift from luxury to overcrowding tells a powerful story about the evolution of San Telmo and Buenos Aires.

Blue line: waterways underground
The Rediscovery and Restoration
Fast forward to 1986, when Jorge Eckstein bought the abandoned property and took on a massive restoration project that lasted nearly 20 years. During the process, workers uncovered a labyrinth of underground tunnels that most of the people forgot and thought was a mystery or a story tail which they heard from the past.
What started as a restoration turned into an incredible archaeological discovery, revealing layers of history hidden beneath the surface.
Why Visit El Zanjón de Granados?
El Zanjón de Granados isn’t just another historical site. It’s an immersive experience that brings Buenos Aires’ history to life. As you wander through the tunnels, you’ll get a real sense of how the city has transformed over the centuries. From natural creeks to a 19th-century mansion and later a home for immigrants, the site tells a story of Buenos Aires city.
This is a must-see for anyone who loves history as I do, architecture, or just exploring the hidden gems of Buenos Aires. The guided tours are fantastic and really help you connect with the stories behind the site.
When to visit El Zanjón de Granados?
You’ll find El Zanjón de Granados in the heart of San Telmo at Defensa 755. You can only enter with guided tours run at specific times, so it’s a good idea to book ahead. Don’t miss the chance to uncover one of Buenos Aires’ best-kept secrets!
Small note: the museum asked me not to take photos of the underground tunnels inside. They want to keep the surprise and secret alive and I respect it 🙂