Baphuon Temple, Angkor Thom, Cambodia

"By the 20th century, much of the temple had largely collapsed, and restoration efforts have since proven problematic: a first effort begun in 1960 was interrupted by the coming to power of the Khmer Rouge, and records of the positions of the stones were lost. A second attempt started in 1995 by a team of French-led archeologists as of 2005 was still ongoing, restricting visitor access. As of May 2006, partial visitor access is once again allowed, though the project is still expected to be underway for another 2 years."

Quoted from en.wikipedia.org/wiki/Baphuon

"The Cambodian civil war broke out soon after the dismantling. As a result, the restorers were banished from the country and many of their local assistants were killed. When war ended and the EFEO restorers under the leadership of Pascal Royere were allowed back, they found that all the documents relating to the dismantling of the Baphuon had been destroyed. As a result of that, they had to piece together 300,000 pieces of this monumental jigsaw puzzle. At first, they tried to use a computer program to make sense of this big jumble. That proved unproductive, so ultimately they relied on their own judgment. "

Quoted from: www.asiaexplorers.com/cambodia/baphuon.htm