Half of all hutongs have been destroyed over the last century. The ones they're rebuilding are the ones that survived destruction. These survivors however are almost unrecognisable from the original middle class courtyard homes, having been built over with 20th century add-ons, the courtyards filled in, and the exterior defaced by shops.
In the past
By the late 20th Century - the garrulous homes had become so subdivided due to the lack of development during the tumultuous 19th and 20th Centuries, despite the booming population, the average resident of Beijing averaged 1 sq metre of living space by the 1980s, with entire families sharing a room, and several families sharing a wing of the original home. Once rich houses had degenerated into slums, hence why the authorities were so unbothered about bulldozing them, despite their antiquity up to 300 years old:
http://cdn.cnn.com
http://insidescoopsf.sfgate.com
After removal of 20th Century add-ons, and rebuilding of the walls:
www.worldatlas.com
www.tour-beijing.com
www.chinasunnytour.com
https://laviezine.com
http://img.timeoutbeijing.com,
www.trip.me/blog