LA COURNEUVE, France — At the foot of the dilapidated Balzac housing tower, an 11-year-old boy bled to death here on a summer afternoon in 2005, stray bullets in his heart and neck. Nicolas Sarkozy, who was interior minister at the time and is now president, arrived the next day in this hard-luck Paris suburb, famously pledging to “clean” the area with a Kärcher, a brand of high-pressure hose.

Six years later, the drugs and violence have not gone from this neighborhood, called the “4000,” a massive gray complex of housing projects that have for decades been an emblem of the troubles of France’s poor suburbs.

Balzac has now been emptied, though, and a spidery mechanical arm tears away at it each day. The towering wall of stained concrete and tile, once 600 feet long and 16 stories high, is to be replaced by a cluster of smaller units, part of a $60 billion nationwide plan to refurbish France’s roughest neighborhoods.

It is hardly the first time such efforts have come to the 4000. Governments have been razing and rebuilding in this neighborhood for 25 years, hopeful that new architecture and new theories about how best to house the poor will solve the problems here. Residents and local officials, though, have few expectations that new walls and fresh pavement, whatever their configuration, can drive a deeper renewal.