Five Things to Know about Syria's Aleppo

Once an economic powerhouse, Aleppo and its surrounding countryside have suffered some of the bloodiest violence in Syria's five-year conflict that has cost more than 300,000 lives.

Here are five facts about the northern city, which has been roughly divided into a regime-controlled west and a rebel-held east since July 2012 and where the government said Thursday it had launched a new offensive.

- War comes to Aleppo in July 2012 -

In April-May 2011, thousands of students demonstrated in Aleppo, which had so far been spared the unrest in Syria since mid-March.

While the student protests were brutally crushed, rebels took control of several parts of Aleppo province which they would later use as launchpads for a massive July 2012 offensive on the city.

The army fought back with tanks, leaving Aleppo divided into east and west. 

The first air strikes in Syria's war followed.

Since then, Aleppo has been split between zones controlled by the rebels and those by the regime, with its province divided up between regime, rebels, jihadists and Kurds.

- Major stake in conflict -

Aleppo, Syria's second city, is strategically vital to all sides in the conflict and the army has made its conquest one of its priorities.

Aleppo's fate is seen as key to the outcome of the war and a possible Russian-backed ground offensive against the rebel-Islamist alliance which controls the east of the city could be a potential turning point.

- A devastated city -

The once-flourishing city with its globally renowned old town and souk markets has been reduced to a site of devastation.

Since December 2013, the army has been using brutal barrel bomb strikes from helicopters and military planes, targeting opposition-held residential neighborhoods, according to the Syrian Observatory for Human Rights and activists.

Use of this particularly destructive weapon has been denounced by the United Nations and international non-governmental organizations.

Rebels have retaliated with deadly rocket fire on regime-held neighborhoods. 

Medics say health conditions in the rebel part of the city, where several hospitals have been hit, are alarming and that medical staff are falling victim to the regular bombardments.

- Last supply route severed -

Since July 17, Aleppo's rebel neighborhoods, home to around 250,000 people, have been totally under siege, after regime forces cut off the last supply route.

The noose has since tightened for the inhabitants, faced with food and petrol shortages as well as soaring prices.

Following a September 12-19 ceasefire which failed to allow the delivery of humanitarian supplies, missiles rained down on rebel-held areas on Friday as the army prepared a ground offensive to retake the city.

The U.N.'s humanitarian chief, Stephen O'Brien, said Monday he was "pained" that aid convoys had not deployed to eastern Aleppo.

According to the Observatory, at least 130 civilians were killed between July 31 and September 8, while more than 700 fighters also died.

- Ancient city -

Provincial capital Aleppo is one of the world's oldest cities to have been constantly inhabited since at least 4,000 BC, thanks to its strategic position between the Mediterranean and Mesopotamia, present-day Iraq.

The manufacturing center, renowned for its textiles, is situated at the crossroads of major trading routes, and numerous civilizations succeeded each other on its soil.

Listed as a UNESCO World Heritage site in 1986, Aleppo's citadel, a jewel of Islamic military architecture in the Middle Ages, was built in stages over three centuries from the 10th century.

It was damaged by a blast in July 2015. Two years earlier, fighting destroyed the minaret of the Ummayad mosque and before that a fire ripped through the ancient souk, partially destroying it.