The oldest manmade object in New York City is getting a facelift.
A conservation project on Central Park's 3,500-year-old Obelisk, also known as Cleopatra's Needle, began last week. Lasers are expected to start vaporizing grime off the monument's surface on Tuesday.
Three lasers, each emitting infrared light at a wavelength of 1,064 nanometers, were designed to deliver enough energy to expand dirt particles so quickly that they are ejected from the Obelisk's2,112-square-foot surface. One of the Nd:YAG lasers was even custom-made for the project.
"The lasers are going to go very gently over every square inch," said Doug Blonsky, president of the Central Park Conservancy.
The meticulous cleaning is part of a joint effort by the conservancy, the Metropolitan Museum of Art and the city parks department to promote the needle's long-term preservation.
"People know us more for dealing with plant materials in the park," Blonsky said. "But preserving the needle is part of preserving Central Park, too."
Preparation for the $500,000 conservation project first began in 2011, when the 69-foot Obelisk was scanned, photographed and surveyed during the most extensive documentation of the monument in its long history. Blonsky said this documentation will help facilitate further study of the monument and other obelisks.
From symbols of ancient civilizations to modern-day war memorials, the meaning of obelisks has evolved over the centuries, said Janice Kamrin, assistant curator of the Met Museum's Egyptian Art Department.
"In Egypt, they were set up at the entrances of tombs and temples to define the sacred space," she said.
This particular obelisk is one of two made thousands of years ago to honor Pharaoh Thutmose lll and installed outside the Temple of the Sun in the ancient city of Heliopolis. At some point, the pair fell and were partially buried in sand near the Nile River, allowing water and salt to penetrate the granite's surface, which caused cracking and erosion of some hieroglyphs.
They were eventually found and taken to Alexandria in 12 B.C. before the Egyptian government gifted one to the United States and another to England in the late 19th century. Transporting the 220-ton monolith from a dock in Staten Island to Central Park alone took nearly six months.
"It would not be easy today," Kamrin said. Since 1881, the Obelisk has remained inGreywacke Knoll.
The park conservancy said experts believe environmental stresses thousands of years ago have made portions of the needle's surface vulnerable. After testing several methods, lasers were determined to be the safest way to clean the Obelisk.
When the laser cleaning is complete in the next few months, adhesive products will be applied to the monument's surface to help conserve the granite.
Despite these measures, supported through private fundraising, Blonsky said the Obelisk is not at risk.
"What you see right now is what you'll see in 500 years," he said.
Learn more about obelisks and Cleopatra's Needle
The Metropolitan Museum exhibition "Cleopatra's Needle" explores the construction and evolving symbolism of obelisks.Running through June 8, the exhibit is located in the Egyptian Art Special Exhibitions Gallery.
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