San Francisco ? Criminals once rotted inside “The Rock,” the Alcatraz Island prison in San Francisco Bay that is now a popular tourist attraction run by the National Park Service.

Soon the tourist experience will have an added, auditory dimension: the slam of the slammer.

In the old days, guards cried, “Rack ’em!” before slamming all the cell doors at once with a grim clang. But since the prison closed in 1963, the big old-fashioned steel bars that locked prisoners in their cells have fallen into disrepair. Now a park ranger on Alcatraz has persuaded a Texas-based prison hardware firm to fix the cell doors in the main block for free. Workers got started this month.

“It’s a very distinct noise,” said John Banner, who served four years in Alcatraz for bank robbery. Now 83, he still recalls the finality of the clanging cell doors. “When they slam shut, they slam shut.”