The transit center replaces the old Transbay Terminal that served bus routes connecting San Francisco to the East Bay. The new building, designed by Pelli Clarke Pelli Architects, is four blocks long and rises four stories above Mission Street between First and Fremont Streets. The ground floor connects to the surrounding streets. The upper level serves as the bus deck, handling dozens of regional and intercity bus routes. A future underground level is designed to accommodate California High-Speed Rail and Caltrain extensions, though the timeline for rail service remains uncertain. The transit center was built adjacent to Salesforce Tower, creating a transportation hub at the base of the city's tallest building.

The transit center's most celebrated feature is the 5.4-acre rooftop park, designed by landscape architects Peter Walker and PWP. The park includes walking trails, gardens, a playground, an amphitheater, and a bus fountain where children play in jets of water. The park offers views of the downtown skyline and is open to the public free of charge. It has become one of San Francisco's most popular urban spaces, an elevated garden that transforms the roof of a bus station into a destination in its own right. The contrast between the industrial function below and the pastoral landscape above captures San Francisco's persistent optimism about what infrastructure can be.

The September 2018 closure, caused by cracks in structural beams fabricated by a subcontractor, raised serious questions about construction quality and oversight. The repairs took nearly ten months and required replacing the damaged beams and inspecting every structural connection in the building. The transit center reopened in July 2019 and has operated without incident since. The episode is a reminder that even the most ambitious civic projects are built by human hands, and that the gap between a building's aspirations and its execution can sometimes be measured in fractured steel.