The white marble bell tower of
Pisa was begun in 1174 as part of
the city's cathedral complex.
When three of the eight stories of
the 185-foot building plan were
complete, the architects noticed
that uneven settling of the
foundation was causing the tower
to lean over 17 feet from the
perpendicular.
The head engineer, Bonnanno
Pisano, tried to compensate for
the problem by making the next
four stories slightly taller on the
side that was leaning. Unfortun-
ately, the weight of the extra
stone caused the tower to sink
even more. Several engineers tried
to find solutions, but nothing
seemed to work. The final story
of the tower was added in the
14th century, nearly 200 years
after the tower was begun.
In spite of cement reinforcement
of the tower's foundation, and
numerous other schemes to rescue
the structure in modern times,
the Leaning Tower of Pisa is still
in danger of collapse.
