The tunnel had ventilation and electric light, and ended almost at the door of the bank, said the police.
It could have been a new heist of the century -- if it hadn't been for a metal rod popping up in the middle of a cobblestone street.
Authorities in San Isidro, Argentina -- the location of the fabled 2006 "heist of the century" -- announced Thursday that they had prevented a repeat crime.
On Wednesday, a parked driver heard a noise in the chassis of his car that turned out to be caused by the rod emerging from the street surface.
After police arrived at the scene on the northern outskirts of Buenos Aires, an excavation found a tunnel beginning in a warehouse about 220 meters from a branch of Macro Bank.
Large amounts of earth had been moved and extraction machines were discovered.
The tunnel was lined with wood, had ventilation and electric light, and ended almost at the door of the bank, according to police. So far, police have not found the would-be robbers.
Investigators said construction took between six and nine months and called the tunnel an engineering feat "better than the one El Chapo Guzman" used to escape from prison in 2015 in Mexico.
The incident was reminiscent of the so-called "heist of the century," which took place in 2006 in the same upmarket town, when criminals, with meticulous planning, stole nearly $19 million from a bank and escaped through a tunnel.
In that robbery, which spawned books, TV series and films, the robbers used toy weapons and left a note in the vault that read "In a neighbourhood of rich people, with no weapons or grudges, it's just money."
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