On
this date in 1964, the Italian government made an announcement:
please, world of engineers and architects, help us prevent the
Leaning Tower of Pisa from collapsing.
Almost
as soon as construction started on this grand bell tower, way back in
1173, the building started leaning one direction. When only three
floors had been built, construction stopped for almost a century.
When work resumed, the chief engineer decided to compensate for the
visible lean by making the new stories slightly taller on the short
side. In 1278, workers reached the top of the seventh floor—and the
tower was leaning nearly three feet! Construction stopped again.
In
1360, builders decided to finish off the tower with an eighth and
final story. Again, a cheat was used to counteract the lean—this
time, the bell chamber was built with a slight slant in relation to
the rest of the tower. By 1370, the structure was declared finished
and declared an architectural wonder. People came from all over to
admire it. Look at the six external arcades! The 200 columns! The
very distinct lean!
 |
| One reason people want to visit the tower is to take advantage of this photo op! |
The
tower leaned just a little more each and every year—although of
course that only made people even more interested in seeing it!
In
the 1500s, the top was 12 feet south of the base. In the 1800s, an
architect was ordered to excavate the part of the base that had sunk
into the ground—and water came up out of the ground, and the tower
lurched another few inches to the south. In the 1900s, Mussolini
ordered engineers to pour concrete into the foundation to reverse the
tilt. But the tower leaned even more inches southward!
Recently
scientists have discovered that the tower was built over the remains
of an ancient river estuary, on ground filled with water and silty
sand. No wonder the building has been sinking!
After
the 1964 call for help, two different attempts to stabilize the
building resulted in even greater leaning. Finally, in 1990, the
Italian government closed the building to visitors out of safety
concerns. Plastic-coated steel tendons were built around the tower, a
concrete foundation with counterweights was created on the north side
of the tower. These measures helped reverse a bit of the learn but
were a bit “unsightly.”
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| Lead counterweights, 1998. This is what I saw when I visited Pisa. |
 |
| This 2004 photo shows no cables-- when I went, there were lots of cables!--and shows people at the top of the tower--which wasn't allowed when I was there. |
In 1999, engineers began to very slowly
extract soil under the north side of the tower—just a gallon of
soil a day—using massive steel cables to stabilize the tower during
the process. By the end of 2001, 18 inches of lean was reversed, and
the tower was reopened to the public.
Of
course, the only time I visited the Leaning Tower of Pisa was during
the 11 years it was closed! Rats!
Also
on this date:
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