Douma, a large suburb of Damascus of about 200,000 people, has long been in rebel hands, and cited as a base from which rebel forces would be able to mount attacks on the capital. It hasn’t worked out that way.
The town is well and truly rebel-held, entering requires crossing rebel checkpoints, while rebel forces patrol the roads as an improvised police force, while local religious leaders operate a court system.
But that control is only skin deep. It’s just a suburb, and its rebel presence makes it a magnet for air strikes. Being so close to the capital, efforts to use it to mass rebel fighters doesn’t work well either, but rather invites yet more strikes.
Interestingly, while the Syrian government has fought hard to reclaim other Damascus suburbs, they seem more-or-less content with letting the rebels keep Douma, never addressing the fall of the Sunni-dominated suburb in public comments, and lobbing regular air strikes.
This likely reflects on both the difficulty of reclaiming such a large suburb and its relative uselessness as a base of operations for the rebel forces, one of those many situations that keeps the battle in Syria stalemated.