Still Leaning After All These Years

The famed Leaning Tower of Pisa is no doubt one of Italy’s most iconic monuments. It is also one of its most endangered buildings, having teetered on the brink of collapse until recently, when conservators and engineers carried out an ingenious plan to reduce the tower’s lean by a mere .5°, buying it several centuries of relief. Sixty meters tall and 20 meters wide, the bell tower was constructed over a 200-year period—interrupted by long periods of inactivity—that began in August 9, 1173. The eight-story, cylindrical structure is essentially hollow, each level accessed via an interior spiral staircase. The tower’s instability surfaced early on, coming to light during construction of its second story in 1272. At that time, masons believed they could correct, if not completely reverse, the tower’s lean by simply adjusting the position of subsequent courses of marble and lightening the weight of building materials and fill. When these efforts failed, further measures were taken to straighten the tower by adding courses of masonry to the south and subtracting them to the north, evident in the construction of the belfry, which has six steps to the south and only four to the north. Today, these “corrections” are noticeable in the tower’s obvious banana shape when viewed from the east or west.

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