HOMS, Syria - It's hard to believe that this was home to thousands of families, but in 2011 anti-regime fighters - followed by Islamic militants - dug in to the neighborhood, and took on the Syrian military.
From the Syrian army position overlooking the old city, the soldiers had a very clear view of the whole area, so the armed militants down below had to find a way to keep out of sight.
Inside the wreckage, a Syrian sergeant showed CBS News how they did it.
The soldiers say militants dug 40 miles of tunnels. They'd got hold of a power drill, and everywhere in this warren of rooms and alleys are stacked bags and barrels full of the dirt they dug out.
The army's response was months of fierce bombardment, but they didn't win.
Instead, there was a U.N. brokered cease fire in May. More than 2,000 militants got safe passage out.
As the Syrian government starts the massive cleanup here, the fighting with Islamic militants has moved a few miles north to the outskirts of the city.
A Syrian army sergeant told CBS News he knows he'll be fighting them again, probably soon.
When asked whether the people of Mosul in Iraq - currently in control of the ISIS, al Qaeda-inspired militants - will face similar kinds of destruction if the Iraqi army battles them there, the sergeant said it will be worse.
"ISIS is much better armed," he said.
For those searching fragments of their lives from the ruins, "worse" is hard to imagine.