Researchers discovered underground passages under the courtyard of Alcatraz Prison

At the top of a rock, on an island in San Francisco Bay, lies a maximum security prison whose secrets and mysteries have inspired dozens of legends and stories not to sleep: the Alcatraz prison.

Powerful criminals like the bird lover psychopath Robert Stroud or the famous mafioso al Capone They slept in prison cells and died in their facilities.

Although the prison closed in 1963 because of the high costs of its maintenance, many puzzles still hover over its walls. More now, a group of researchers from the University of Binghamton, New York, confirmed that under the prison yard there are pbadages, tunnels and ventilation ducts "in the shelter of the bombs".

Archaeologists have used non-invasive technology locate historical faults. Using high-tech radars and laser scans, the team discovered the structure, which she said was part of a former military base of the 19th century.

"The remains of these historic buildings they were a few inches from the surface and miraculously preserved impeccably, "said Timothy de Smet, chief archeologist of the investigation, in a statement.

A military fortress to defend the California coast

According to the study, military constructions were allegedly built around 1840, when Mexico reportedly lost control of California. For US authorities, the location of the island, in the middle of California Bay, was a ideal place to erect a fortress from which to defend their coasts.

When the prison was built in the early 20th century, construction workers they buried the buildings and corridors of the military base and they raised on their foundations "The Rock", name with which the prison is also known.

The discovery is important from the historical point of view, marks a transition between brick and masonry structures that were traditionally used in the construction of coastal defenses towards earthen buildings.

The discovery of the team led by Timothy de Smet confirms one of the main hypotheses that experts have been defending for years: the existence of historic pbadages and recesses under the ground of Alcatraz.

In addition, give credit to one of popular legends The most famous of the place, who told that an extensive network of tunnels went through the basement of the shocking prison.

"It was wonderful to find the story under our feet and to be able to visualize it for the public " said the head of the investigation.

Alcatraz prison is now a kind of "museum of terror" in which curious visitors can visit the facilities in which some of the most famous criminals lived.