(covers information from several alternate timelines)
Alcatraz was a small island in the San Francisco Bay, famous for being the site of a maximum-security prison in the 20th century. On a clear day, the island could be seen from San Francisco's Presidio.
In the alternate reality, a visitors center had been built on the island. In 2259, the island was seen on a map of the Bay Area. This map was part of a collection of graphics and video media that were seen on a powerwall in the offices of Admirals Christopher Pike and Alexander Marcus at Starfleet Headquarters. Three days later, the damaged USS Vengeance, on a course to Starfleet Headquarters, slammed into the island. The impact of this collision destroyed both the prison, the visitors center, and a good portion of the island, resulting in an unknown number of causalities. Moments after this event, the mortally wounded starship crashed into the bay, then regained altitude briefly before plowing into the city. (Star Trek Into Darkness)
A version of Kathryn Janeway from the year 2404 told her past self in 2378 that one could see Alcatraz from USS Voyager's ready room on a clear day, because Voyager was a museum located on the Presidio in that timeline. (VOY: "Endgame")
- In the novelization of Star Trek Into Darkness, the impact with Alcatraz is what arrests the Vengeance's momentum enough to prevent the ship's hull from destroying Starfleet Headquarters, as Khan intended, though not enough to prevent the ship from crashing into the San Francisco waterfront.