The 415 Mission Street building is called the "Salesforce Tower" formerly known as the Transbay Tower. Its build directly on top of the Transbay Terminal.
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After Completion it will be tallest building in San Franciso at 1,070 ft (326 m). The Tower is supposed to be finished in 2016.
Links: virtualglobetrotting.com, www.skyscrapercity.com