San Francisco Bay Bridge, California

The San Francisco–Oakland Bay Bridge connects on the San Francisco side at the South of Market neighborhood, after spanning Pier 26 and the Embarcadero, and touches ground next to a new condominium tower. This marks the western end of Interstate 80, after a 2,899-mile journey westward from the George Washington Bridge in New York City. The elevated highway divides the city, establishing a transition from the high-rises of downtown and the financial district to the relatively flat expanses of the former industrial and logistics area to the south. The shoreline around downtown has been significantly extended with fill over the years. During the excavation of the site for the Infinity Condominiums here in 2005, for example, three blocks from the current shoreline, the remains of the Candace, an early China trade and whaling ship built in Boston in 1818, was unearthed.

The Bay Bridge is one of the most impressive bridges in the country, though, like the City of Oakland it serves, it is usually upstaged by its flashier neighbor, San Francisco's Golden Gate. The bridge's four mile span is composed of two halves. The Oakland side is supported on pilings resting on the sediment of the bay. For this reason it is vulnerable to violent motion and damage during earthquakes (it was this span that partially collapsed in the 1989 Loma Prieta quake). The damaged span had to be completely replaced with a new one running along side it (one of the largest contemporary civil works projects in America), at a cost of $6.416 billion, reopening to traffic in 2013 . At the mid-point of the bridge is the Yerba Buena Island Tunnel, a 540-foot long tunnel serving both directions of traffic, one on top of the other. At 78 feet wide, it is said to be the largest diameter road tunnel in the world. The western part of the bridge is a suspension bridge, with a huge concrete footing, sunk deep into the sediment of the bay, that, at the time of construction, was the heaviest structure in the world, containing more concrete than the Empire State building. The base of the midspan tower above this concrete anchorage structure is largely hollow, and has a dramatic, cathedral-like room inside. The bridge is one of the the busiest toll bridges in the nation, averaging 270,000 cars per day, generating millions of dollars in revenue every month.