The front line that slices through Aleppo separates the ancient Syrian city's residents into two distinct worlds, the only thing uniting them the fear of stepping into a sniper's sights.

This feeling is eerily similar on each side of the line, scanned by gunmen perched in once residential buildings.

On one side, the charred hulks of buses are used as roadblocks; on the other, canvas masks alleyways so people can cross without becoming targets.

On the government side, 24-year-old Ahmad Abu Zeid has to cross six streets overlooked by snipers to get home in the Suleiman al-Halabi district.

Before leaving the house each morning, he prays.

"If they shoot me, let them hit me in the head or heart. Let them kill me, because I don't want to be crippled for life."

Aleppo has been split in two since a major rebel offensive in July 2012, in a division reminiscent of the infamous Green Line that divided Beirut from 1975 to 1990.

"One minute, everything is calm. Then suddenly it's chaos. Once 42 shells fell here, 16 of them on our building. One destroyed our kitchen," Abu Zeid told AFP.

Syria has been ravaged by war for nearly four years, but Aleppo -- once the nation's thriving commercial capital -- is the only city to have been split in two.

The front line stretching north to south is some 20 kilometres (12 miles) long.

- Scanning for prey -

West of the line, Khaled Khanju in the rebel-held district of Sakhur shares Abu Zeid's fears.

"We have to cross four or five streets in full view of the (army) snipers to get our supplies," he said.

Another Sakhur resident, Abu Wajdi, told AFP: "So the snipers in Suleiman al-Halabi don't see us, we put a bus in the middle of the street.

"What have civilians like us done to deserve this?"

Nearby, a sniper crouched behind a wall searched for prey through his telescopic sight.

In the regime-held Armenian district of Midan, residents have stretched canvas across the street to make it hard for rebels some 100 metres (yards) away to see them.

The screen cannot protect everyone, however. Every time he goes home, pillow-maker Samuel Krikorian risks his life as he lifts the canvas and enters the rebels' field of vision.

"I lift the canvas and just go. It's very dangerous, and a man was killed right in front of me. But what can we do?" he sighed.

"Every morning I wait until I see people on the street... It's a way of conquering my fears."

- Wreaking havoc -

In rebel-held areas, barrel bombs dropped by regime helicopters are another constant danger, while rebel mortar rounds also wreak near-daily havoc on the other side.

Thirteen-year-old Seif lives in Sheikh Khodr, some 200 metres from the rebel lines.

"Every time I go to school or the shops, I run," he told AFP.

As is all too often the case in wartime, children have shown a remarkable capacity to adapt to the extraordinary circumstances battle brings.

In Suleiman al-Halabi, 12-year-old Mohammed walks home from school with his friends, giggling as they pass an army post.

"When the rebels shoot, we run," said Mohammed who lives in a building that has been disfigured by multiple mortar strikes.

"My friend Mohammed Hajo was wounded in the hand by a sniper. He never came back to school," he told AFP.

Despite the violence, children on both sides still play on the streets, often on their bikes.

"Before the army kicked the rebels out of Suleiman al-Halabi, we were the only family that remained, and in the evenings we would lock the front gate of our building with a chain," Abu Zeid said.

Other residents returned after the army recaptured the area.

"Where are we supposed to go?" Abu Zeid asked.

Across the line, a man named Abu Ahmad echoed him: "We have nowhere else to go. We have to stay here."