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Intrepid tourists travel thousands of miles and spend thousands of dollars just to experience historic marvels with their own eyes. The irony is that much of what they're seeing is the work of ongoing upkeep, the replication of what it probably used to look like.
To mark the 2001 reopening of the Leaning Tower of Pisa after a fix that kept it from falling over, we take a look at the preservation efforts of other epic monuments.
Left:
Egypt's Sphinx has seen many phases of conservation, from its uncovering by Thutmosis IV in 1400 B.C. when only its head was visible, to a multiphase restoration project that began in 1989 and continues today. Weather and modern wear on the ancient statue require nearly constant upkeep.
Photo: Library of Congress/Maison Bonfils

: Photo: Library of Congress/George P. Hall & Son, N.Y.C.
Even Lady Liberty in New York Harbor needs a little love sometimes. Closed to the public and covered in scaffolding from 1984 to 1986, much of Statue of Liberty's iron framework was replaced with stainless steel, and holes in the copper skin were patched and repaired. The job required $230 million in private funding.

: Photo: Library of Congress/Detroit Publishing Company
England's Stonehenge is actually the result of three phases of building and restoration.
The first stage occurred around 3100 B.C., which included the construction of a circle of timbers and digging of a perimeter ditch using animal bones.
The site was then rebuilt around 2300 B.C. using bluestones from the Prescelli Mountains in Pembroke, South Wales. The monument we see now was the result of another update that happened around 2100 B.C. The bluestones were dug up and replaced by larger sandstone pieces from Marlborough Downs 20 miles from the site. Today, less than half the original monument is standing.
Current restoration efforts include the Stonehenge Project, which (or maybe, witch) seeks to move roads away from the site and build a visitor center nearby.

: Photo: Library of Congress/Keystone View Co.
Erected by some of the greatest sculptors, architects and artists of fifth-century-B.C. Greece, the Acropolis reflects the power and wealth of Athens at its peak. Since then, the structure has suffered extensive damage, and its preservation is ongoing.
Restorers are now using a combination of traditional techniques and lasers in their efforts. The marble technicians use tools similar to those used by the original architects, while lasers clean intricate details like the battle-scene carvings.

: Photo: Corbis
The Great Wall of China consists of architecture from several eras and has been battered over the years by both natural and human elements.
Inner Mongolia contains the largest section of any province, and has launched a three-year restoration project at an estimated cost of $14.3 million.

: Photo: Library of Congress
The Taj Mahal attracts 3 million visitors a year while sitting on the banks of the most-polluted river in India, the Yamuna. The Archaeological Survey of India recently enacted a restoration project to clean the marble facade using clay mudpacks to remove the yellow tinge of air pollutants, much as women in India use mudpacks to help their complexion. This famous facial is estimated to cost $200,000.

: Photo: Associated Press/Plinio Lepri
An estimated 500,000 people lost their lives in gladiator battles and hunting simulations in the Roman Colosseum. Medieval builders also ripped off its stones to use for their own constructions, and it suffered extensive damage from an earthquake in 1349. Since then it's been under almost constant restoration and planning.
A survey conducted in 1997 using lasers and infrared light provided a very precise map of the building, revealing useful information on structural deformation. Half the Colosseum's floor was rebuilt with wood to protect the underground rooms and passages in 2000, and the effects are being monitored before the second half follows suit.

: Photo: Dean Conger/Corbis
A visual icon of Russia, St. Basil’s Cathedral in Moscow's Red Square was built on uneven ground and has formed cracks as it's settled. At one point, a government report warned that it was slowly sinking into the ground.
Restoration work has kept the building intact and saved much of the artwork, but the cathedral will likely need ongoing attention for as long as it stands. Plans to develop a luxury-hotel complex and underground garage next to it have raised further concern over the structure's integrity.
