A highly sophisticated restoration team is painstakingly reassembling the Parthenon of Athens—a classic Greek building that has suffered from wars, earthquakes, and disastrous previous restoration attempts.

The Parthenon’s builders created dauntingly precise yet subtle curves throughout the structure, giving the building its legendary grace.

Etched in the marble itself, the restoration team discovers traces made by the ingenious tools the stonemasons used to carve the blocks with such speed and precision.

Experts examine the extent to which the Parthenon’s symmetry and visual harmony is dependent on a system of mathematical proportions.

Two hundred miles from Athens, faint lines left behind on another Greek temple reveal the technique the early engineers used to sculpt the Parthenon’s perfect curves.