San Francisco's future public transportation hub, The Transbay Transit Center, has been called the "most expensive bus terminal in the history of humankind" by a city supervisor.

Its astronomical costs match the developer's ambitions. Upon completion in 2017, the $2.3 billion Transbay Center will connect eight Bay Area counties through 11 transportation systems. It includes up to 100,000 square feet of retail space and a rooftop park.

It's unclear if the "most expensive" superlative is true. But it might be. For comparison, New York's Port Authority Bus Terminal — the largest and busiest bus terminal in the world — cost an estimated $24 million when it was constructed in the mid-20th century.

While construction on the Transbay Center is far from over, these stunning renderings provided by the developer's website give us a glimpse inside.