As the battle for Aleppo closes in on the historical centre in northern Syria, heritage sites in one of the world's oldest cities are being damaged and experts fear the worst is yet to come.
In Bab al-Nasr neighbourhood, a Free Syrian Army rebel pointed to a gaping hole in the base of the delicately chiselled minaret of the 700-year-old Mahmandar mosque.
"Bashar al-Assad's forces don't respect anything, not our history, not our religion," said the fighter, who sported a short black beard and green bandana, broken glass crackling under his feet as he walked into the prayer room.
So long as the rebels maintain a position next to it, the mosque is likely to be hit again by shelling or sniper fire from the nearby Aleppo Citadel, the iconic medieval fortress that crowns the UNESCO-listed ancient city.
Rebels seeking to seize Syria's second city and oust Mr. al-Assad have been conquering street after street, inching closer to the Old City.
Loyalist forces who have relinquished control of the ground have pounded rebel positions with tank shells or from the sky with helicopters and fighter jets, often causing extensive damage.
According to UNESCO, five of the country's six World Heritage sites have been affected by the violence: Damascus, Palmyra, the Crac des Chevaliers crusader castle, the ancient northern villages (or Forgotten Cities) and Aleppo.
But the threat facing the immeasurable heritage of Aleppo, considered the best-preserved ancient city in the Middle East, is perhaps the greatest.
The Citadel itself was hit earlier this month and its Mamluk-era gate severely damaged.
The fortress, which in ancient times could shelter a garrison of 10,000 men, is currently held by loyalist troops, but the rebels are trying to circle it and claim the army has only one supply route left.
"From a military point of view, the Citadel is still almost as important as it was 500 years ago but even if we surround it completely, I think it would be hard to capture it," said Abu Mohamed, a rebel commander.
The castle, which sits atop a steep artificial hill towering above the area, is said to have been successfully stormed only once, by Mongol ruler Tamerlane in 1400.
UNESCO chief Irina Bokova has expressed alarm at the situation in Aleppo and urged both sides to protect the city's cultural heritage.
The UN agency said it was also co-ordinating with partners such as Interpol and neighbouring countries "to prevent the smuggling of antiquities as a result of theft in museums and historical sites."
Some artifacts have already been stolen from the Palmyra museum and Aleppo's rich national museum is a stone's throw from the fast-moving front line.
Some of Aleppo's most spectacular khans are still in regime-controlled zones but ancient souks where the smell of burning garbage has replaced the ageless scent of laurel soap and spices are deserted and being disfigured by the war.
"Usually, there are lots of tourists around here. Governments in Europe, for example, value their cultural treasures," said Abu Abdallah, a young fighter, as he sidled along shuttered shops to stay out of a sniper's line.
"But all this means nothing to Bashar al-Assad," he said, walking past a building with a plaque announcing the world's oldest bathhouse.