Great Wall Of China: Extra Miles Discovered

An extra 180 miles of the world-renowned ancient Chinese monument were uncovered after a two-year government mapping study, according to an official report.

The study used mapping technologies such as infrared range finders and GPS devices to show extra portions of the wall - hidden by hills, trenches and rivers - that stretch from Hu Mountain in northern Liaoning province to Jiayu Pass in western Gansu province.

The newly mapped parts of the wall were built during the Ming Dynasy to protect against northern invaders.

They were covered over time by sandstorms that moved across the arid region.

The newly found parts mean the Great Wall - which Chinese emperors began building 2,000 years ago to keep out Mongols and invaders - spans about 3,900 miles through the northern part of the country.

The project is to continue for another year to try to map sections of the wall built during the Qin and Han Dynasties.

Ming 1368AD - 1644AD

Qin 221BC - 206BC

Han 206BC - 9AD

Recent studies by Chinese archaeologists show that sections of the wall in Gansu are being reduced to "mounds of dirt" by sandstorms and may disappear entirely in 20 years.

They blame destructive farming methods in the 1950s that "desertified" large areas of northern China.

Also, portions of the wall in Gansu were made of packed earth, much less resilient than the brick and stone used in much of the wall's construction.

China has in recent years begun restoring parts of the wall as well as trying to rein in commercial development on and around it.

The wall's modern sections around the Chinese capital date from the Ming Dynasty, including those restored since the Communist Party took power in 1949, and several areas - including the most popular, Badaling, just north of Beijing - draw hundreds of thousands of visitors each year.

Tourist encroachment also has been a problem in recent years, with state media saying that, near Badaling, almost every brick on a popular section of the wall has been carved with people's names or other graffiti.