We jump out of the car and run across a "sniper alley", darting through a hole in the opposite wall. What this wall once protected is now nothing but rubble, across which we scramble. Our heads are low as we run, hunched up and through another wall, across a road strewn with detritus, through another hole and bounding over mounds of rubble. We climb a makeshift ladder, and into a building, where fighters conceal themselves behind concrete columns, leaning out to fire inaccurate bursts down the road.

My shirt is but a sweat-soaked layer of cloth between my skin and the flak jacket. My cameras clang against the rickety, metal contraption that passes for a ladder as we clamber into another building. Shots ring out; the deeper, more deadly sound of a sniper rifle, contrasting the crack of the katiba's Kalashnikovs.

And then we enter The Labyrinth. Down flights of stairs and into apartments. Where once walls divided neighbours, sledgehammers have created doorways. The intimacy of bedrooms, of living rooms, has been smashed apart as men with guns crawl from house to house, their residents long since left.

A white gown hangs on the door of a wide-open wardrobe, its wooden back splintered apart. Into this wardrobe we climb, but the Narnia on the other side is not that of C. S. Lewis; the Lion on the other side is the head of the regime, and his fighters are the Witch.

In one kitchen stands a fighter wearing a black, martyr's headband, his head adorned with bold, white Arabic script proclaiming "there is no god but God". "This is the front line" they tell us.

Beside him stands a man in military fatigues, a gilet bearing the revolutionary flag on the left of his chest. His head is wrapped in a black and white keffiyeh, leaving just a slit for his eyes. He is contrasted by a young fighter, who wears a pink t-shirt, his long hair covered by a black, "Ché" beret. He would cut the image of "the Revolutionary" anywhere in the world.

When I first encountered him, he was firing from the cover of a concrete column. Now, in this kitchen he lights up a cigarette. "Don't take a picture of me smoking," he says, "my Dad doesn't know I smoke."

From the courtyard outside this kitchen, the FSA hold their positions. Many have left, they tell us, but this group is one of the few defending against their enemy's advance. "We have these guns" one tells me, holding an AK-47, "and RPGs against their tanks." They sit and wait for a tank to pass, using their precious—and limited—rocket propelled grenades against them. The Assad army has superior numbers and armaments, but they don't appear keen on street fighting without the support of tanks and air cover. The rebels claim to have destroyed three tanks in Salaheddine alone, this morning.

Ten minutes screeching drive away, on the outskirts of the neighbourhood, a small group of fighters peer around a wall at another government sniper position. Shots ring out and plaster flies above a window behind them; three bullet holes inscribe a triangle 12 inches below a hole in the brickwork that conceals an FSA sniper. Their comrade's gun has fallen silent, and the rebels around me scream into a radio to see if their sharpshooter is still alive. He confirms it by firing once again at his enemy, guided by a rebel who peers into a broken shard of mirror through binoculars, to confirm his shots.

Despite all of this fighting, the bullets and the bombardments, people still live here. In the Old City, the FSA has positions severed by a road covered by a government sniper. The rebels run across this road, firing their Kalashnikovs with one hand as they dart across.

A civilian in a white jalabiya runs towards us, across the "sniper alley". He complains to the FSA commander that his roof is being used by FSA gunmen, and that it is endangering his family. He's not wrong, I think.

The tall, broad commander, a macho-type, shouts back at him as he cocks his weapon and points the barrel at the man. The rebels all join in, shouting and giving him light slaps and kicks. They tell him that he is doing nothing for the revolution. One pulls up the shutter to a deserted shop in what was once this bustling market. They shove him inside and yank down the shutter, where he remains, incommunicado, for some 20 minutes. When he is released, he must run back across the sniper alley to return to his family, and his compromised home.