Baphuon Monument in Cambodia reopened after completion of decade long Restoration Work

An ancient Angkor temple in north-western Cambodia was reopened to the public on 3 July 2011 after the decades-long renovation project described as the world's largest puzzle was completed.

The restoration of the 11th-century Baphuon monument, one of the country's largest after Angkor Wat was celebrated with a lavish ceremony attended by Cambodian King Norodom Sihamoni and French Prime Minister Francois Fillon.

The finished project is the result of half a century of painstaking efforts by restorers who took apart the crumbling tower's 300,000 sandstone blocks and then piece them back together.

Cambodian people expressed their profound gratitude to France for completing the 10-million-euro ($14m), French-funded undertaking.

French-led team of archaeologists dismantled Baphuon in the 1960s because it was falling apart and then laid out its many stone blocks in the surrounding jungle. French-led team of archaeologists dismantled the pyramidal building because it was falling apart as a result of the heavy, sand-filled core that was putting pressure on the thin walls.

However, the efforts to rebuild the pyramidal structure were interrupted by the civil war in 1970. After the civil war when the restoration work restarted, the records needed to be reassembled as reassemble it were destroyed by the hardline communist Khmer Rouge which took power in 1975.

In 1995, when the area was again safe to work in, the project that came to be known as the world's biggest three-dimensional puzzle was restarted. The French government-funded project was restarted under the leadership of architect Pascal Royere from the Ecole francaise d'Extreme-Orient (EFEO). The team carefully measured and weighed each block and then relied on archive photos stored in Paris, drawings and the recollections of Cambodian workers to figure out where each part fits.

Built around 1060 by King Udayadityavarman II in honour of the Hindu god Shiva, Baphuon, was the country's largest religious building at the time, 35 metres high (114 feet) and measuring 130 by 104 metres (426 x 340 feet). In the 16th century, a 70-metre long reclining Buddha statue was built into a wall on the second level using stones from the top of the temple. These two phases of construction, hundreds of years apart had further complicated the restoration process.

The Angkor region was the seat of the medieval Khmer empire.