Rationale: The leaning tower of Pisa is one of the wonders in the world, it's beauty and historical facts fascinates many tourist and visitors. What makes the Leaning tower as one of the best romantic place in Italy is its remarkable past and legend pertaining to lovers visiting it. They say most lovers would have happy relationship if they wish at the tower of Pisa. Well it is up to you to believe it or not, but the tower of Pisa is really a best romantic place not because of its stories but because of its extraordinary beauty.

^{courtesy of "http://www.xs4all.nl/~pisa0/pisa.htm" by Sr. Bas Pisa}

The Tower of Pisa was built to show the rest of the world the wealth of the city of Pisa. The people of Pisa were very good sailors and they conquered many lands, including Jerusalem, Carthago, Ibiza, Mallorca, Africa, Belgium, Britania, Norway, Spain, Morocco, and other places. But they had only one real enemy, the people from Florence. And to show how well they were doing they started to build a really useless belltower to go with the rest of the buildings near it - the Cathedral, Baptistery, and Cemetery. Yes people the Tower of Pisa is nothing more than a bell tower, but because my last name is Pisa I find it a very interesting tower. They started to build the tower in the year 1173 that means the foot of the tower. After a while the war with Florence started again and they stopped. In 1180 the restarted and in 1185 they had finished the 1st., 2nd., and the 3rd. floor. And again war with Florence, which of course meant that they put all their money in warfare. In this year the tower started to lean to one side, so while they were building, it was already the leaning tower of Pisa. They must have been thinking that a bell tower without bell wasn't a bell tower so the put some bells on the top of the 3rd. floor in 1198. After a another war with guess who...... Florence, they started again for a period of nine years, from 1275 till 1284. But they didn't have any reason to show off anymore since they had lost a big sea battle in 1284 against the fleet of Genoa. This was because they were betrayed by their own count. Count Ugolino della Gherardesca was locked up with his whole family in the tower of Gualandi. The people of Pisa threw the key in the Arno River and the count and his family died of starvation. In 1319 they finished all the floors. And finally they put the bell tower on top of it in 1350. In 1392 Pisa was sold to Florence, a big humiliation for the people of Pisa. The started a rebellion but in 1406 they had to surrender because they were under siege and everybody was dying of starvation. In 1499 they started another war against Florence who were using the people of Pisa as slaves. And again the brave but unfortuned army of Pisa lost and that is the and of the history of Pisa. They never managed to gain the wealth as in the early years, and now it is a small city somewhere in Italy and they are still showing off with their tower.

History and Tourist Information

^{courtesy of Francesco Gambino & Fiorella Morabito, University of Pisa}

The laying of the first stone of the Tower took place August 9, 1173. This assertion is precisely affirmed in the inscription situated on the right of the door that enters into the monument. So had begun construction of one of the most unusual monuments of all times, whose history continues to the present as a circumstance often fictionalized.

The building of the Tower, and especially its completion, represents the last element in the compliment of the celebrative complex of monuments that enrich the Piazza dei Miracolo. At the same time, the four representative monuments (Cathedral, Baptistry, Bell Tower, Monumental Cemetery), by the intentions of those who were entrusted with the realization of the plan, demonstrate the considerable level of brilliance and power reached by this Marine Republic and they testify to posterity. Through the works of the great religious architecture of its towns, the indisputable Pisan prominence reached from the galleys on the Tirreno Sea to the coasts of the Near East.

The absence of precise written references places doubt on whoever had initially planned the Tower. Tradition attributes the work to Bonanno Pisano, in conjunction with William of Innsbruck. But the recent hypothesis does not seem at all out of place, considering recent reserach, that the credit goes to Diotisalvi instead. Finally, according to Vasari, Nicola Pisano deserves the credit, along with his son Giovanni, who could not have been strangers to the construction of the best of the Pisan towers (whether or not the temporal references would specifically recognize it). Certainly they were involved in the subsequent phases of the work and in the studies of its unusual static behavior. In any case, to put aside the real identity of the designer, considerable skills are apparent in the one first to plan the bell tower, one who showed great technical capability and a good dose of boldness.

And, in fact, it must be recognized that the foundations of the imposing construction have been situated at an inferior depth of three meters, on a bedding of dry stones. As though it was planned, the actual work was halted, beginning in 1184, suspended at completion of the third story, about ten years after the beginning of the construction, due to a yielding of the ground that had caused the first leaning of the constructed tower, with an appraisable sinking between 30 and 40 cm and an initial lean of about 5 cm.

And therefore displaced by an inadequate foundation, a repair plan was needed for the already tilted Pisan bell tower.

In the opinion of Professor Piero Pierotti, an architectural historian, the construction materials of significant weight and the functional characteristics created by the staircase, preventing reduction of the masonry toward the top, left few options to resolve the lean. Therfore, determined to resume the job in 1275, over a century after laying of the first stone, it came to be that Giovanni of Simone undertook the construction of three more floors. In 1284, the six gallery floors were completed, carrying the height of the construction to 48 meters. The accomplished technician mitigated, though still not level to the eye, the effect of the inclination by raising up one side of the galleries on the upper floors, partially correcting the lean of the bell tower.

At that time the lean of the Tower was more than 90 cm., a difference that could be taken as a tormented mutation of the Tower, but it did not distress those people who were most affected by its construction and its completion. Long phases of delay during the construction, dictated, most probably, by any small war or political disruption, made the bell tower "rest", and, most importantly, the Tower was able to settle into the ground and stabilize its most famous lean.

TOWER BASICS

Official Name: TORRE PENDENTE DI PISA

Function: Bell Tower (Campanile)

Original Architect: Bonanno Pisano

Architect who realized that the Leaning Tower could not be straightened:

Tomasso di Andrea da Pontedera (1275)

Years Built: 1173-1350

Latitude: 43.7167 (43° 43' 0" N)

Longitude: 10.3833 (10° 22' 60" E)

Elevation of Piazza dei Miracoli: About 6 feet, (2 meters) (DMS)

First Construction Stop: 1178 (War with Firenze)

Year in which lean became obvious: 1178 (Third Story)

Height at which lean became obvious: 10.6 meters (35 ft.)

Level at which Tower Straightens to North: 5 (About 110 meters)

Second Construction Stop: 1185 (War with Firenze)

Later Construction Stop: 1284 (War with Genoa, Major Sea Battle Defeat)

Height: 55.863 meters (185 feet). 8 stories.

Outer Diameter of Base: 15.484 meters

Inner Diameter of Base: 7.368 meters

Weight: 14,700 metric tons

Thickness of Walls at the Base: 8 feet

Direction of Lean: 1173-1250 North, 1272-1997 South

7th Floor Completed: 1319

Bell Tower Completed: 1350 First Bells added: 1198 (Third Floor) Total Number of Bells: 7, tuned to musical scale Largest Bell: L'Assunta (The Assumption). Three and a half tons, cast in 1655. Oldest Bell: Pasquarreccia. Address: Campo dei Miracoli - the "Field of Miracles", Pisa, Italia Year cement injected into base, (blamed for lean acceleration): 1934 Steps to Bell Tower: 294 Number of visitors who climbed to top in 1989: 700,000 Date Closed to Public: 7 January 1990 Date Re-opened to Public: 15 December 2001 Weight of Lead added on North side (picture above): 600 tons (1995) Amount of tilt recorded overnight in September 1995: 2.5 mm (0.07") Weight of Lead added after overnight tilt in September 1995: 230 tons Rate of Fall in 1990: 1.2 mm (1/20") every year ("Un millimetre per anno") Source: The Guardian (London) August 19 1997 Amount of tilt correction from 1990 - 1999: 25 mm (about 1.0") Amount of tilt correction from 1999-2001: 43.8 cm (about 17.25") Date that Tower was last at current tilt: 1700

Romantic and best tourist spot

Imagine you decided to spend a romantic weekend in Tuscany. And imagine you're driving around Pisa, hence deciding for a quickie visit to the Piazza dei Miracoli, a.k.a. Piazza del Duomo. Standing in a large green expanse, Piazza del Duomo houses a group of monuments known the world over. These four masterpieces of medieval architecture - the dome, the baptistry, the campanile (the 'Leaning Tower') and the cemetery - had a great influence on monumental art in Italy from the 11th to the 14th century and are today part of the UNESCO Heritage.

The Dome of Santa Maria Assunta, a medieval building, whose construction began in 1064 by the architect Buscheto (father of a distinctive Romanic style), is a Latin-cross shaped Cathedral, with a large structure of marble, calcar and stone more than 100 meters long, with a large dome. The different styles of the impressive facade are beautifully blended to create a unity of unsurpassed harmony. The interior of the Cathedral is solemn. There are five aisles (three in the transept) and two galleries overlooking the central nave. The columns supporting the round arches come from different places and belong to different times. In the middle of the nave, near the inner wall of the cathedral, is a long line of imposing granite colonnades, which are almost all antique and have capitals of Corinthian style. The women's gallery with little loggias is located above the nave. The spectacular XIII century Pulpit by Giovanni Pisano in the middle of the Cathedral, was reassembled in 1926. Its beautiful octagonal structure, with sculptures and reliefs, is an outstanding example of the transition period of European art from the Romanesque style to the dramatic Gothic forms. The circular baptistry was begun in 1152 and finished a century later by Nicola and Giovanni Pisano. Recently Italian musicologists cracked a five century-old acoustic code to reveal that Christianity's largest baptistery is a musical instrument, designed to mimic the pipes of a church organ. The acoustics beneath the 75-meter (250ft) cupola are so perfect that it must be either an incredible coincidence or the work of genius. For many years it was believed that the inclination of the Leaning Tower was part of its design, but today we know that the Tower was designed to stand vertically and started to lean during its construction, when three stories high; attempts to compensate for this during its construction give the tower a slightly curved shape. The 180 ft (55m) Leaning Tower is the bell tower, or campanile, for the Dome of Santa Maria Assunta. Its construction started in 1173 and continued, off and on, for the next 200 years. By the 1990s, the tower was tilting more than 13 ft from the vertical and restoration efforts were made in 1993 and again in 1995, reducing the tilt to 11'8". The present restoration is predicted to preserve the tower's stability for some 300 more years. Before leaving the Piazza, do not forget to visit the Camposanto and - if you do not suffer from vertigo - enjoy a panoramic view of the city from the Leaning Tower.

Galileo and the Leaning Tower of Pisa

^{courtesy of Jim Loy}

Galileo Galilei is reported (see addendum) to have dropped a ten-pound weight and a one-pound weight off the Leaning Tower of Pisa, and proved that both fall at the same speed. Of course, a more general principle was being demonstrated, the fact that objects of any weight fall at the same speed (with the same acceleration, actually). Does this experiment fit the bill? Does it, in fact, prove that objects of any weight fall with the same speed or acceleration?

At first thought, since Galileo (or anybody) could not measure speeds with perfect accuracy, he could never prove that these two weights fell with the same speed. But, the alternative hypothesis, predicted by Aristotle, was that the ten-pound weight would fall ten times faster than the one-pound weight. Galileo clearly shattered Aristotle's hypothesis. And the experiment was more or less proof of Galileo's hypothesis.

Aristotle was not a person to perform experiments. The folks back then believed that all knowledge could be deduced from basic principles. Well, Galileo also based his hypothesis on basic principles. Let me describe how I reason it out. Let's say that you have three identical one-pound weights, side by side. You drop all three, and they all fall at the same speed, being identical. Then you link two of them together with a spider web. Is this now a two-pound weight? When we drop the three weights, will the two linked by the spider web now fall twice as fast? I doubt it. If we link them with a string, will they fall twice as fast? With several strings, with glue? It seems to me that when we attach two weights with glue, that they are still two weights falling at the same speed that they did when they were separate, and that ten of them (a ten-pound weight, in other words) would still fall at the same speed. Galileo was bright enough to confirm this with experiments.

We all know that some objects (a feather, for example) fall much slower. The metal weights were dense enough that gravity overwhelmed air resistance. Galileo was performing an experiment about gravity. Air resistance was merely a small complication which could be ignored. In the absence of air (in a vacuum), the feather falls at the same speed as a ten-pound weight. Astronauts on the moon performed this experiment, and the feather fell at the same rate as a metal weight. Actually, that experiment has been performed thousands of times, by students, in partial vacuums here on earth.

Some people criticize the formulas and laws of physics, for applying only to idealized conditions. In physics, you hear the phrases, "ignoring air resistance," or "ignoring friction," or "ignoring outside forces," etc. Well, a formula or physical law which takes into account all possible forces, is often so complicated that it becomes useless. Instead, you start with the simple law, like Galileo's hypothesis above, and then make small corrections for the outside forces, if you have to. Then, you get a much more basic understanding of the principles involved.

Addendum:

Galileo described the above experiment in his writings, reasoning much as I do above (as I was amused to find out). But he never claimed to have performed it. Had he actually performed the experiment, it is likely that he would have reported that. So, science historians feel that he never actually did the experiment.

Galileo's results (as opposed to Aristotle) became obvious from Newton's laws of motion, and his law of gravity, which were published several decades after Galileo's death.

It would seem that Einstein's General Relativity (a more accurate law of gravity) says that a heavier object actually does accelerate very slightly faster than does a lighter object, in a vacuum.

Incidentally, the Leaning Tower of Pisa began to lean before it was half built. The clue is that the tower is also bent. The builders obviously bent it to compensate for the leaning of the lower portions. So the lean is greater at the bottom than at the top. Efforts have been made to stop it from leaning further (as otherwise it will fall down eventually) including injecting concrete into the ground underneath. I have not heard if these efforts have been completely successful.