They are a marvel of engineering. Their function is purposeful yet poetic. And they've inspired musicians, painters, and writers for centuries. Beyond the sheer practicality of crossing ravines and water, and getting from point A to point B, bridges, perhaps more so than any other type of structure, spark romance. No matter the type of bridge -- suspension or swinging, or a fallen tree over a river -- the act of crossing it forces you to pay attention to where you are, and where you are going. A bridge takes you on a journey.

"Bridges make possible something that is seemingly impossible," says Richard L Cleary, a professor of architecture at the University of Texas at Austin, and the author of Bridges, a study of American structures. But a bridge that connects two continents, like the Bosphorus Bridge in Turkey? Now who would have thought that was possible?

In Pictures: World's 10 Amazing Bridges

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While the Brooklyn Bridge and the Golden Gate Bridge are two of the most iconic bridges in the world, looming large in the mind as well as in the skylines of New York City and San Francisco, it was the Romans who first wowed the world with their structural engineering and bridge-building capacities. The Ponte San Martino Bridge, built between 25 BC and 1 BC in northern Italy [Images] near Turin, is still in use today. Whether it's ancient or new, sometimes the sheer mass of a bridge, or its unusual design, or the harsh environment that it traverses, make us stop in wonder at how it was constructed.

With that in mind, TravelandLeisure.com scoured the globe in search of the most amazing bridges on the planet. Some are noteworthy because of their "how did they do that?" factor, as with the world's highest suspension bridge, the Royal Gorge Bridge, which stretches 1,000 feet above Colorado's Arkansas River. Others were included because of legend and notoriety, like the Baroque Bridge of Sighs in Venice -- said to be the last walk that criminals would ever take, leading them to their execution, and, ironically, one of today's most romantic and recognized symbols of the storied seaside city.

In Pictures: World's 10 Amazing Bridges

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Other bridges still are unique for completely different reasons; in May 2005, the Bosphorus Bridge was host to a tennis match between Venus Williams [Images] and Turkish grand slammer �pek Senoglu, making it the first-ever match to take place between two continents. And the Gateshead Millennium Bridge over England's [Images] River Tyne is its own garbage collector; each time it opens to let by ships, garbage rolls down into specially designed litter traps.

A bridge, says Cleary, "puts one in a different relationship with the landscape." Perhaps the ultimate case in point: the Hangzhou Bay Bridge, which crosses the Qiantang River at the Yangtze River Delta on the East China Sea. When it opened in May 2008, it became the longest ocean-crossing bridge in the world, but its design took nine years of planning by nearly 600 experts because of the rough waters of the bay. This symbol of China's economic boom -- a stayed-cable bridge with six lanes of traffic -- may not be as aesthetically pleasing as some other bridges, but its impressive scale and conquering of the elements makes it all the more beautiful.

So if you have the chance, seek out one of these amazing bridges and do the "impossible" and make the journey across.

In Pictures: World's 10 Amazing Bridges

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