Golden Gate Bridge

San Francisco, California and Marin County, California

The Golden Gate Bridge is a suspension bridge spanning the Golden Gate, the beginning of the San Francisco Bay onto the Pacific Ocean. As part of both United States Highway 101 and California Route 1, it connects the city of San Francisco on the northern tip of the San Francisco Peninsula to Marin County.

The Golden Gate Bridge had the longest suspension bridge span in the world when it was finished in 1937 and has become an internationally acknowledged symbol of San Francisco and California. Since its completion, the span length has been surpassed through eight other bridges. It still has the second longest suspension bridge main span in the U.S., after the Verrazano-Narrows Bridge in New York City. In 2007, it was ranked fifth on the List of America's popular Architecture by the American Institute of Architects

The Golden Gate Bridge spans the Golden Gate, a narrow, 400-foot (120 m) deep strait that serves as the mouth of the San Francisco Bay, between San Francisco at the northernmost tip of the San Francisco Peninsula, and the Marin Headlands at the far southern end of Marin County. Although close through proximity, the two sides of the strait are split by important natural obstructions. Crossing the strait directly by boat is insecure because of strong currents and lack of suitable landings. Ocean tides drive an average of 528 billion gallons (2 billion cubic meters) of water every six hours, at peak currents exceeding 5.6 mph (2.5 m/s). Circumnavigating the Bay, even so, involves a trip of several hundred miles and crossing several major rivers.