El Zanjón de Granados

A nearly 200-year-old mansion situated above a series of underground tunnels that date back to the Buenos Aires's earliest settlements, El Zanjón de Granados is now a museum that offers one-hour tours to visitors. Some parts of the structure, including a wall comprised of seashell mortaring, date back even further.

Rescued by amateur historian and Argentine chemical engineer Jorge Eckstein in 1985, the structure took 17 years to restore to its current condition. More than 130 truckloads of debris were unearthed from the structure's tunnels. In that debris, Eckstein discovered French tiles, African pipes, English china, and many other precious objects.

Displays in the museum are varied and include an old, underground slave cell and photographs of the area that date back to the 19th century.