The principal challenge in restoring the Parthenon was undoing the effects of
earlier accidents, natural disasters, and poor restoration, not to mention
millennias' worth of punishment from rain, pollution, wind, and visitors.
The most damaging accident at the Parthenon occurred in 1687, when the Turks
used the structure as an ammunition dump. During a Venetian bombardment of the
Turkish-held Acropolis, a powder magazine in the building blew up, destroying
its center. More damage occurred in the wake of a 1981 earthquake. Previous
restoration has wrought its own damage as well. Workers had to bring down 300
or so stones, for instance, that previous restorers had repositioned at random
on the lateral walls in 1842-44. They will soon reconstruct the lateral walls
using authentic stones.
The most recent restoration at the Parthenon, still underway, is thorough and
historically accurate. This new effort has as its aim the conservation of the
structure and surfaces, maximum protection for the sculptures, correction of
the position of previously restored stones, and additional restoration of
certain parts, mostly using fallen stones preserved in situ.
For the treatment of marble, workers have used both the varied tools of
traditional marble sculpture and modern electrical tools. The latter include
two electrical cranes, lifting devices, a pantograph for marble cutting, and
metal scaffolding. All told, they brought down ancient marbles weighing in
total approximately 300 tons for conservation before repositioning them in
their original places. They have used titanium to reinforce broken stones and
have designed clamps in such a way that, in the case of excessive stress, the
clamps break before the marble.
Principal source: The Parthenon Reconstruction Project