A city without cars would be very strange, right? But Venice is such a city.

Venice is in the north-east of Italy. It wasn't built on land, like Beijing or Shanghai, but on more than 110 islands. Sea water is everywhere around the city.

Even so, travel isn't difficult. The waterways have always been the best way to get around. There are 117 waterways and more than 400 bridges that can guide you where you want to go. People in Venice move from place to place by boat.

Water makes the city special, but it is also a big problem. Sometimes tourists will have such strange experiences. One moment they walk across the Rialto Bridge, and there's nothing special. But when they come back to the bridge an hour later, it's underwater and everyone is wearing rain shoes.

Once, people used too much underground water. This made the city get lower little by little. Now the city has gone down by 23 centimetres. Another problem is the rising sea water. The temperature has risen over the years. This has made the ice of the Arctic Ocean melt. Every year, high water hits the city in autumn and winter. When a lot of water comes, more than half of the city is underwater.

Scientists are trying different ways to stop the city from getting even lower. The Italian government has asked some of Italy's biggest companies to build the MOSE project, which was planned to be built under the sea water to stop the rising water. Anyway, this project is helping solve the problem.

Shanghai began as a fishing village in the 11th century, but by the mid-18th century it was an important area for growing cotton. After 1842 when China lost the Opium War with Great Britain, the British realized that Shanghai was in an excellent location to serve as a seaport for the densely populated Yangtze River Plain. They forced the Chinese government to allow English traders to settle on the wastelands outside the city walls.Later, French, American, and Japanese traders also came to Shanghai and were allowed to live in certain territorial zones without being under the Chinese laws. The foreigners built whole new sections of Shanghai, including homes, stores, factories, and office buildings. Thousands of Chinese poured into Shanghai in search of jobs, most of whom settled in the old part of the city. As a result of all the foreigners, Shanghai became greatly influenced by Western culture.

During the 1900s, opium sales along with the gambling brought in big profits. After the Anti-Japanese War in 1945, the Nationalist Chinese government took over the city. In 1949, Shanghai was liberated and administrated under the Communist Chinese government. Since the 1990s, Shanghai has developed quickly and has become a new international metropolis in China and will host the World Expo in 2010.

Here are some of the most beautiful medieval castles in the world.

Eltz Castle, Germany

Eltz Castle sits on top of a hill surrounded by a thick forest. Located in Rhineland-Palatinate due to its secluded (僻静的) position, it is a world away from other castles. Eltz Castle has seen its fair share of conflict but was never destroyed over the centuries. Interestingly, Eltz Family has possession of the castle to this day.

Edinburgh Castle, Scotland

One Scottish beauty is the Edinburgh Castle. Sitting on top of Castle Rock, it overlooks the capital of Scotland. Unsurprisingly, considering the majority of medieval castles had strategic locations, the key was being able to see the enemy and remain difficult to reach. During the First and Second Wars of Scottish Independence, the ownership of the castle changed between the Scottish and the English several times.

Vianden Castle, Luxembourg

Even though its origin dates back to the 10th century, Vianden Castle was steadily built over three centuries between the 11th the 14th century. Vianden Castle is an example of the Romanesque style with semi-circular arches, even though there were Gothic additions later on. Just like many other medieval castles, Vianden Castle lies on top of a hill overlooking the town of Vianden.

Bran Castle, Romania

Bran Castle sits atop a former Teutonic Knights stronghold (要塞) dating back to the early 13th century. It is approximately 2,500 feet above sea level and rises from between surrounding trees. It overlooks the picturesque village of Bran, and the several towers and turrets (塔楼) give it a mysterious atmosphere.