Without a question, the most well-known image of the Tuscan city and one of the most recognisable structures in all of Italy is the Leaning Tower of Pisa.
The bell tower of the Cathedral of Santa Maria Assunta, situated in the centre of Piazza del Duomo in Pisa, is known as The Leaning Tower.
It was constructed between the 12th and the 14th centuries in the Romanesque style to a design by the architect Bonanno Pisano, measuring 57 metres in height, increasing to 58.36 metres if you also take the foundation level into account.
Its construction started in August 1173 and was completed in 1178 to about a fifth of the fourth story. Before Giovanni di Simone recommenced work on the building in 1272, construction had been suspended for almost a century.
The seventh and eighth floors were reached after six years of work. The work was once more suspended in 1278. The belfry was finally constructed in 1360 by Tommaso di Andrea Pisano, and the bells were set in the belfry in 1370.
The tower’s main structure is a hollow cylinder with an outside and an inner facing. Rubble, or irregular brick and stone blocks glued together with lime, fills the hollow. San Giuliano marble lines the outside and interior walls up to the sixth storey. Lighter limestone makes up the higher portion.
There are two chambers inside the Tower structure:
- The sala del Pesce, which is located at the base of the tower and is so named because it has a bas-relief of a fish. Because it is the hollow portion of the tower, it is a room without a ceiling;
- On the seventh story, the bell tower. It is open to the sky and encircled by the walls of the top walkway. The tower’s ground level can be seen through a hole in the middle.
- Three flights of stairs are also a part of the building, the first of which is interrupted and goes from the ground to the sixth story.
- The third, another spiral staircase, goes from the seventh level to the top. The second spiral staircase connects the sixth and seventh floors.
Seven bells make up the tower, the largest being “L’Assunta,” which was cast in 1655 and weighs 2.5 tonnes in total. Cast in 1262, “Pasquareccia” is the oldest. The belfry is 294 steps up from the ground.
The tower has seven floors, or levels, which stand in for the seven paths that Christ took, the seven phases of life, and the seven harmonic spheres that the soul must travel through with the aid of the Holy Spirit’s seven gifts in order to approach God. A unique and original feature is a series of arcades and he curves with six loggia floors.
The building is tilted at an angle of 3.97° to the vertical axis. This tilt is caused by the subsidence of the ground on which the base of the bell tower rests.
This happened during the first phase of the project, when work was interrupted at the halfway point of the third floor. This was due to the soft, clayey, unstable soils that usually compacted.
In 1275 construction resumed on the third floor, also built to straighten the tower.
In fact, his three floors tend to curve in the opposite direction of the slope.
Over the centuries, the tower has never collapsed during construction or restoration.
The reason is simple. The center of gravity is in the area of the tower base.
In reality, the center of gravity is inside the building. This is where the weight of the entire tower is concentrated. Connecting the center of gravity and the center of the tower base creates a straight line that fits within the area of the tower base. The tower collapses when the flannel moment centroid line is no longer in the base. There is a tower near the Baricentro Line, which is no longer a base.
In addition, extensive work has been done over the years to balance the weight of the tower and slow future falls due to soil movement.
The interior of the Leaning Tower of Pisa is nothing more than a giant cylinder. Only a spiral staircase leads from the base to the bell tower. The stairs are quite narrow. He can only go up and down one visitor at a time. You can clearly see the tilt of the tower when you climb the stairs.
Once you understand why the Leaning Tower of Pisa is leaning, you naturally wonder if it won’t fall.
Despite the visible slope, the construction is very solid. It prevents tipping because the center of gravity line is in the area of the tower base. Over the years, it has also been the focus of extensive stabilization work. Specifically, it was closed from January 1990 to June 2001. Structural work took him 11 years to reduce the building’s slope by 44 centimeters.