Alcatraz is an island in San Francisco which has an old penitentiary which is no longer in use.
History
Scooby-Doo and Scrappy-Doo
The gang took a group tour there and encountered the Lady Vampire of the Bay.
The Richie Rich/Scooby-Doo Show
Shaggy Rogers, Scooby-Doo, and Scrappy-Doo tried to keep an enemy spy from stealing an important secret package there.
What's New, Scooby-Doo?
Season two
The gang took a tour with Julian Libris as part of their investigation into the San Franpsycho. They were attacked by the monster; it also sailed away in the tour boat, leaving them stranded. This left them highly suspicious of Julian.