Aleppo is one of the oldest continuously inhabited cities in the world. "The jewel of Syria" is a Unesco World Heritage site and was a popular tourist destination. Now much of Syria's largest city is in ruins. Aleppo has been split roughly in half between opposition groups in the east and government troops in the west.

Rebel-held areas have been flattened and abandoned after thousands were killed by "barrel bombs" – steel drums full of shrapnel and explosives – dropped by Syrian government aircraft.

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Men search for belongings in the rubble of damaged buildings in al-Kalaseh neighbourhood of Aleppo on 17 November, 2014Reuters
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A Syrian boy walks with his bicycle in the devastated Sukari district of Aleppo on 13 November, 2014AFP
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Syrians try to rescue wounded people from a burning building following an air strike by government forces on the Kalasa neighbourhood of Aleppo on 12 November, 2014AFP
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A member of the Syrian Civil Defence walks through a cloud of dust after an air strike by Syrian government forces in Aleppo on 11 November, 2014AFP
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A rebel fighter runs through dust towards an area damaged by barrel bombs dropped by Assad's forces in Aleppo's al-Shaar neighbourhood on 6 November, 2014Reuters

The momentum in the nearly four-year-old conflict is widely seen to be with President Bashar al-Assad's forces, reportedly bolstered by fighters from Iran, Lebanon, and Afghanistan.

His troops have slowly encircled rebel positions this year trying to cut supply routes. Islamic State (IS) militants are also trying to take nearby communities.

French Foreign Minister Laurent Fabius said that the coalition fighting IS must now save Aleppo. "Abandoning Aleppo would condemn 300,000 men, women and children to a terrible choice: the murderous siege of the regime's bombs or the barbarity of the Islamic State terrorists," Fabius wrote.

"It would condemn Syria to years of violence. It would be the death of any political perspective and would see the fragmentation of the country run by increasingly radicalised warlords. It would also export the internal chaos of Syria towards already fragile neighbours Iraq, Lebanon and Jordan."

Turkish Prime Minister Ahmet Davutoglu has said Assad's forces are committing "large massacres" by barrel-bombing areas under the control of the Free Syrian Army (FSA), an umbrella term for the dozens of armed groups fighting Assad.

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Syrians try to rescue wounded people from a burning building following an air strike by government forces on the Kalasa neighbourhood of Aleppo on 12 November, 2014AFP
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A man cries at a site hit by a barrel bomb in the al-Marjeh neighbourhood of Aleppo on 12 November, 2014Reuters
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A man carries a child, injured by what activists said were barrel bombs dropped by warplanes loyal to Syria's President Bashar al-Assad, in Aleppo's al-Shaar neighbourhood on 6 November, 2014Reuters
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A boy rides his bike past a destroyed building in Aleppo on 5 November, 2014AFP
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Buildings reduced to rubble in the Kalasa neighbourhood of Aleppo are pictured on 28 October, 2014AFP

Apart from Aleppo and areas in the south of the country, "the FSA has been decimated and no longer effectively exists," Fayez al-Dweiri, a retired Jordanian general who follows the Syrian war closely, said.

Thousands of rebels have died fighting Islamic State this year, a war that has overshadowed and undermined the struggle to topple al-Assad. Now the Nusra Front — al-Qaida's branch in Syria, which previously was also fighting against IS — has turned on more moderate factions.

"This is the end of the Free Syrian Army," said Alaa al-Deen, an opposition activist. "It's the beginning of an Islamic emirate."

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Free Syrian Army fighters prepare a locally-made mortar launcher during clashes with forces loyal to Syria's President Bashar al-Assad on the Amerya front in Aleppo on 5 November, 2014Reuters
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A Free Syrian Army fighter prepares a locally-made mortar shell in the Bani Zeid neighbourhood of Aleppo on 10 November, 2014Reuters
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A Free Syrian Army fighter rests beside weapons inside a safe house on the Amerya frontline in Aleppo on 5 November, 2014Reuters
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A Free Syrian Army fighter fires his weapon through holes in a wall in the Al-Maysar neighbourhood of Aleppo on 2 November, 2014Reuters
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A rebel fighter calls on his comrades during clashes with regime forces in Aleppo on 31 October, 2014AFP
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Rebel fighters watch television as they rest inside a room on the Karm al-Tarab frontline in Aleppo on 30 October, 2014Reuters

The Syrian civil war has killed close to 200,000 people and forced more than three million refugees to flee the country, according to the United Nations.

Residents in the government-controlled western part of Aleppo live in fear of shelling and explosions even as they try to go about their daily business.

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Women take selfies at Fairuz restaurant in the government-controlled Mogambo neighourhood of Aleppo on 15 November, 2014AFP
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Syrians dance at a night club in the government-controlled part of Aleppo on 15 November, 2014AFP
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Aleppo's historic citadel, which is controlled by forces loyal to Syria's President Bashar al-Assad, is seen from a rebel-controlled area of Aleppo on 8 November, 2014Reuters

Staffan de Mistura, the UN envoy to Syria, has called for an incremental truce in Aleppo – an idea that al-Assad has said is "worth studying." Many opposition activists said they believe residents would welcome a truce, after three years of relentless shelling, bombing and displacement.

But they expressed fears the government would merely exploit a truce in Aleppo to gather its forces to fight elsewhere, and questioned how a ceasefire could work when Islamic State fighters are trying to sweep through the area.