Archaeologists find tunnels under former Alcatraz prison
Find confirms suspicion the prison was built over a civil war-era military fortification
Alcatraz Island in San Francisco, California is now a major tourist attraction with ferries every 15 minutes from the mainland and visitor numbers of 1.7 million each year
Archaeologists have found a series of buildings and tunnels under the notorious former US prison Alcatraz.
The find confirms a long-held suspicion of historians, that the prison, on an island in San Francisco Bay, was built over a Civil War-era military fortification.
A study published in Near Surface Geophysics last week said archaeologists used ground-penetrating radar, terrestrial laser scans and historical maps and photographs.
They found fully buried structures, ammunition magazines and tunnels.
Historians believe that workers built over existing structures when the prison was constructed in the 20th century.
Alcatraz first came to the attention of the US government after it wrestled control of California from Mexico in the 1840s.
It is now a major tourist attraction with ferries every 15 minutes from the mainland and visitor numbers of 1.7 million each year. – AP