The Spanish explorer who first came upon the island off San Francisco bay noticed it housed many pelican birds, and named it “Arcatraz” — the Island of the Pelicans. When the U.S. took over and built a prison on the site, the name of Alcatraz took on a meaning of certain kind of incarceration, impossible to escape save for the prisoners being able to turn into pelicans themselves.

On this day, August 11, in 1934, Alcatraz received its first batch of “most dangerous” prisoners: serial killers, murderers, men who were only hardened in previous prisons, men who were thought to be unreformable.

Alcatraz was designed to hold 330 prisoners, but never held more than 275 — along with 90 guards, a high ratio, but necessary to secure the worst of the worst. And of course despite its escape-proof myth, several men did manage to gain brief freedom outside its walls. Several were shot dead trying to make their escape, and two made it into the churning water in makeshift canoes. They were never heard from again.