History Lost Amid the Destruction of These Syrian UNESCO World Heritage Sites

PHOTO: The temple of Baal-Shamin in Palmyra, Syria in an undated photo.Getty Images
The temple of Baal-Shamin in Palmyra, Syria in an undated photo.

As Syria enters its sixth year of war, the list of what has been lost is almost incomprehensible.

The Syrian Center for Policy Research claims 470,000 Syrians have been killed, double the United Nations estimate. It also claims 1.9 million Syrians have been injured.

But in addition to the horrific toll of human suffering, the nation’s physical landscape has been decimated.

UNESCO, the United Nations organization responsible for identifying significant cultural landmarks around the world, says all six of the Syrian UNESCO World Heritage sites have been destroyed or damaged since war began in 2011.

And photos tell the story of how these culturally significant ruins will never be seen in the same way again.

The destruction of some of the sites, like Palmyra in eastern Syria, has been well-documented.

In October, ISIS destroyed Palmyra's 2,000-year-old Arch of Triumph, once a top tourist attraction in the region.

PHOTO: An aerial file photo taken in January 2009 shows part of Palmyra in Syria.Christophe Charon/Sipa USA/AP Photo
An aerial file photo taken in January 2009 shows part of Palmyra in Syria.

PHOTO: An undated photo released Aug. 25, 2015 on a social media site used by Islamic State militants purports to show smoke from the detonation of the 2,000-year-old temple of Baalshamin in Syrias ancient caravan city of Palmyra.ISIS via AP
An undated photo released Aug. 25, 2015 on a social media site used by Islamic State militants purports to show smoke from the detonation of the 2,000-year-old temple of Baalshamin in Syria's ancient caravan city of Palmyra.

ISIS deems ancient relics a form of idolatry and against their strict interpretation of Islamic law, but the destruction of such sites is also believed to be a valuable source of income on the black market.

PHOTO:DigitalGlobe imagery of the Baalshamin temple in Palmyra, Syria collected on June 2, 2015 (before and then After) on Sept. 2, 2015.DigitalGlobe/Getty Images
PHOTO:DigitalGlobe imagery of the Baalshamin temple in Palmyra, Syria collected on June 2, 2015 (before and then After) on Sept. 2, 2015.

Other places on UNESCO's list are less well-known, like the ancient city of Bosra, which was once a stopping point for caravans on the way to Mecca, Saudi Arabia.

While some archaeological sites are targeted by criminals and armed groups, others, like Bosra, are just another casualty of war.

PHOTO:The Italian maestro, Ricardo Muti, leading late Sunday, July 25, 2004, more than 300 singers and musicians at the roman Bosra stadium, which was built 2,000 years ago in Daraa province, south of Damascus and accommodates some 16,000 people. Youssef Badawi/AP Photo
PHOTO:The Italian maestro, Ricardo Muti, leading late Sunday, July 25, 2004, more than 300 singers and musicians at the roman Bosra stadium, which was built 2,000 years ago in Daraa province, south of Damascus and accommodates some 16,000 people.

PHOTO: Protesters carry opposition flags and chant slogans during an anti-government protest inside a 2nd century Roman amphitheater in the historic Syrian southern town of Bosra al-Sham, in Deraa, Syria, March 4, 2016. Alaa Faqir/Reuters
Protesters carry opposition flags and chant slogans during an anti-government protest inside a 2nd century Roman amphitheater in the historic Syrian southern town of Bosra al-Sham, in Deraa, Syria, March 4, 2016.

The Crac des Chevaliers and Qal’at Salah El-Din are historic castles from the Byzantine, Crusader, and Islamic periods that were damaged during fighting between government and rebel forces.

"These two castles represent the most significant examples illustrating the exchange of influences and documenting the evolution of fortified architecture in the Near East during the time of the Crusades," UNESCO writes on its website.

PHOTO:Krak Des Chevaliers is pictured in this undated file photo in Homs, Syria, before the start of the civil war. LightRocket via Getty Images
PHOTO:Krak Des Chevaliers is pictured in this undated file photo in Homs, Syria, before the start of the civil war.

PHOTO:Syrian government forces inspect items left by rebel fighters in the famed Crusader castle, Krak de Chevaliers in the Homs region, March 21, 2014, after they recaptured the castle the previous day. AFP/Getty Images
PHOTO:Syrian government forces inspect items left by rebel fighters in the famed Crusader castle, Krak de Chevaliers in the Homs region, March 21, 2014, after they recaptured the castle the previous day.

Its latest State of Conservation report on the castles says the Syrian government is taking actions to build support structures to preserve the site and is "preparing execution drawings for the implementation of additional consolidation, restoration and reconstruction works."

The remaining three Syrian World Heritage sites include the ancient cities of Aleppo and Damascus, and the ancient villages of Northern Syria.

PHOTO:This 12th-16th-century set of buildings was included into the UNESCO World Heritage list in 1986 and is now destroyed due to the civil war in Aleppo, Syria. Michael Alaeddin/Sputnik via AP Photo
PHOTO:This 12th-16th-century set of buildings was included into the UNESCO World Heritage list in 1986 and is now destroyed due to the civil war in Aleppo, Syria.