字幕列表 影片播放 列印英文字幕 Welcome to the magnificent Tower of Pisa, perhaps more commonly known as the Leaning Tower of Pisa. This 56 meter high tower is world famous, not only for its beautiful looks, but mainly for its heavy tilt. But why is the tower leaning the way it does? I tell you that in just a minute. The Tower of Pisa was built as a part of Piazza dei Miracolli and is the piazza's third oldest structure, after the Cathedral and the Baptistry. More precisely, an inscription located to the right above the entrance to the tower, tells us that the construction started on august 9th, 1173. One of the purposes of the tower was to serve as the bell tower for the cathedral. However, the main purpose of the tower was to show the world the wealth and power of the city of Pisa. During these times, Pisa with its mighty fleet was one of the strongest and most powerful Italian cities. They had successfully raged war all over the Mediterranean Sea and the new tower needed to reflect these victories. This is why the tower in front of you looks completely different than an ordinary bell tower. A few years after the construction started, the tower began to lean towards the southeast. This due to the fact that the tower was built on a poorly laid foundation, only three meters deep. The tower was also built on weak, unstable subsoil which allowed the foundation to slightly shift direction. This caused one side of the tower to sink into the ground. When this happened, five years had passed since the start of the construction and the tower had progressed to the third floor. With this, the construction halted for almost a century. The halt in construction was not because of the problems with the leaning tower, but because the Pisans were almost continually engaged in battles with Genoa, Lucca and Florence. The halt in construction allowed time for the underlying soil to settle. This most likely saved the tower, as without the interference of wars, the tower would almost certainly have toppled. In 1272, the construction of the tower resumed. In an effort to compensate for the tilt, the engineers built upper floors with one side taller than the other. This made the tower begin to lean in the other direction; instead of southeast it began to lean southwest. The completion of the tower would however take another 100 years, as several smaller wars interfered. With the completion of the bell chamber in 1372, one of the most unusual monuments of all times stood finished. The tower is been subject to several restoration and stabilization projects; not only due to the towers instable nature, but also due to its age and exposure to wind and rain. The first stabilization project was initiated in the 1960ies, when the engineers realized that the tilt was increasing in combination with softer foundations. Many methods for stabilizing the tower were discussed, including the addition of 800 tons of lead counterweights to the raised end of the base. Later, in 1990, a massive restoration and stabilization project was initialized. During this project, the tower was closed to the public and the bells were removed to relieve some weight. The plan was to straighten up the tower by removing 38 cubic meters of soil from underneath the raised end using special drills. In order to keep the tower stabile during this daring project, several heavy cables were cinched around the third level and anchored several hundred meters away. Apartments and houses in the path of the tower were also vacated for safety. In 2001, the project was finally completed and the tower had been straightened by 45 centimeters, returning to the exact position it had in 1838. After these massive reconstruction and stabilization efforts, the tower was reopened to the public in December 2001 and was declared stable for at least another 300 years. Prior to restoration work performed between 1990 and 2001, the tower leaned at an angle of 5.5 degrees, but the tower now leans about four degrees. This means that the top of the tower is almost four meters from where it would stand if the tower were perfectly vertical. If you feel ambitious, and isn't afraid of heights, I can highly recommend a trip to the top of the tower. While almost 300 steps will take some time to climb, it will give you a great view of Piazza dei Miracolli and the city of Pisa. Today, the Tower of Pisa is the region's number one tourist destination -- attracting people from all over the world. It is listed as a UNESCO World Heritage Site and inarguably one of the world's most famous towers.