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Bridges have been around ever since humans began to move themselves -- and their goods -- from one place to another. Early bridge engineers had to do little more than fell a tree across a ravine or stream, but they soon discovered that they could span greater distances and haul heavier loads by putting more time and energy into their structures. Roman engineers perfected the stone arch and used it to build aqueducts -- bridges that conveyed fresh water great distances -- and similar structures to carry traffic across streams and rivers. But the Industrial Revolution took bridge building to new heights and even greater lengths. The Brooklyn Bridge, completed in 1883, was the longest spanning bridge in the world -- until Scottish engineers completed the Firth of Forth Bridge just seven years later. A new century brought longer, more amazing bridges. In 1937, the Golden Gate Bridge stretched its 8,981-foot (2,737-meter) back over the treacherous waters of the San Francisco Bay.
Today, engineers continue to test the limits of science and imagination. They experiment with innovative materials, designs and methods of construction. Their finished products move cars and trains. They also move people's souls. What follows is a survey of some of the most breathtaking bridges of the modern era. We've limited ourselves to just 10 bridges, but not to any particular region of the world. Our first stop is the Hangzhou Bay Bridge in China. The Chinese are not new to bridge building. The Anlan Bridge, a suspension bridge first constructed in A.D. More than 1,700 years later, in the Jiangsu Province, Chinese engineers completed a project that includes a 4,888-foot (1,490-meter) suspension bridge and a 2,575-foot (758-meter) cable-stayed bridge. Known as the Runyang Bridge, it was the country's longest bridge -- for a while. Today, the Hangzhou Bridge, which opened in May 2008 after nine years of planning and construction, holds the honor as China's longest bridge. It stretches a mind-boggling 22 miles (36 kilometers) across the Qiantang River at the Yangtze River Delta on the East China Sea.
That's almost 25 times longer than the Runyang Bridge and nine times longer than Japan's pride and joy, the Akashi Kaikyo Bridge! The cable-stayed bridge snakes across the open ocean, carrying six lanes of traffic in both directions. Commuters have to pay 80 yuan, or almost $12, to cross it, but the toll fee is nothing compared to the bridge's price tag of 11.8 billion yuan ($1.72 billion). If it lasts as long as expected -- 100 years -- it should have a long time to pay for itself. There we'll find the Strait of Bosporus and the next amazing bridge on our list. Modern bridges, such as the Hangzhou Bay Bridge, owe much to structures that preceded them. Bridge building took a great leap forward in the 19th century as engineers in Europe and the United States applied the principles of physics to erect some of the best-known bridges the world has ever seen. The Brooklyn Bridge has been a landmark of New York City since it opened in 1883. Likewise, the Tower Bridge, which began carrying traffic over the Thames River in 1894, is practically synonymous with London.
The Strait of Bosporus, also known as the Istanbul Strait, connects the Black Sea to the Sea of Marmara. It also separates Asia from Europe. As such, it holds great strategic value during times of war and peace. Although attempts to bridge the narrow body of water date back to the Persian Empire, the most impressive structure didn't open for business until 1973. That's when engineers completed the Bosporus Bridge, a 4,954-foot- (1.51-kilometer-) long suspension bridge that remained the only bridge in the world linking two continents until the Fatih Sultan Mehmed Bridge suspended its roadway above the strait nearly 15 years later. Even with a companion bridge stealing some of its glory, the Bosporus Bridge remains a grand sight, especially at night. Thanks to an LED lighting system, the bridge's towers and zigzagged cables glow brilliantly in different colors. Each direction has three lanes for vehicles, plus one emergency lane and one sidewalk. Pedestrians were allowed to access the bridge until 1977, when authorities stopped the practice for safety reasons.
They temporarily suspended the rule in May 2005 when Venus Williams and Ïpek Senoglu played a tennis match on the bridge to promote the inaugural Istanbul Cup in Turkey. Fans gathered on two of the bridge's lanes to watch the players trade volleys from Asia to Europe and back again. The next bridge on our list has never hosted a tennis match, but it has become one of ngland's hottest tourist attractions. In a bascule bridge, one or two pieces of the bridge deck, known as leaves, swing up to provide clearance for boat traffic passing underneath. They open quickly and efficiently but aren't the most elegant pieces of architecture. This was the challenge facing engineers when officials in Gateshead, England, announced a contest in 1996 to design an innovative cycle and pedestrian bridge to span the Tyne River. The new structure had to allow ships to pass underneath without blocking the view of other nearby bridges or interfering with cultural activities taking place on either bank.
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