A 12th-century crusader castle was hit in an air strike by the Syrian regime on Friday, leading to the partial destruction of the Crac des Chevaliers World Heritage Site in western Syria.
Video posted on YouTube shows a huge blast, followed by one of the castle's towers going up in flames. Internal damage is shown, including a pile of rubble and a hole in the ceiling.
According to the activist filming the video, the damage was caused by a MiG air strike. "Look at this, world. This is Bashar al-Assad bombing the Crac des Chevaliers," he said.
The world-famous castle was built between 1142 and 1271 and was declared a Unesco World Heritage Site in 2006. Before the conflict, the fortress was one of Syria's leading tourist attractions and hosted summer festivals.
Situated on a hill, it has been a favourite position of rebel snipers. In a bid to retake the province of Homs, the Syrian army has been shelling the surrounding area for several months.
Crac des Chevaliers is not the only historic site to be targeted in the civil war, which has claimed more than 90,000 lives.
"Most sites are in danger and already most of them have been destroyed or partially destroyed. Both sides use the critical sites for the front line," said Ossama Abdel-Meguid, a member of a committee set up to protect Syrian heritage by the International Council of Museums. Crac des Chevaliers, along with the Fortress of Saladin in the north, was considered one of the best-preserved crusade-era castles. Other endangered sites include the Old Cities of Damascus and Aleppo and the ruins at Palmyra.