National Geographic : 1916 Oct
TITE BAPTISTERY, CATHEDRAL, AND LEANING TOWER OF PISA The cathedral was built in commemoration of Pisa's great naval victory in 1063. It is constructed almost entirely of white marble. The Bap tistery (in the left foreground) dates from 1153. It is too feet in diameter. The Leaning Tower, or Round Campanile, was completed in 1350. Galileo availed himself of its oblique position in his studies of the laws of gravity. It is now generally accepted that its out-of-plumb position is the result of sinking foundations rather than of intention on the part of the architect. It is 14 feet out of the perpendicular, 8 inches of this being due to subsidence since 1800 (see page 339).