“I am proud of my father — he is not corrupt,” reads one message, in bold black letters, next to an ArtLords mural. It is painted on the blast walls of a building belonging to the Finance Ministry, long considered one of the most corrupt institutions in Afghanistan.

In one of Kabul’s main squares, the blast walls protecting a military base are painted light olive. A tiny park, with two benches and some grass and rosebushes, has seemingly grown in front of the walls, providing a respite for visitors to one of the city’s busiest hospitals, around the corner, or the Public Health Ministry, across the road.

But the view from the benches is largely blocked by a makeshift rest stall for the police officers stationed at the roundabout. The stall is boxed by blast walls. Beyond the stall, one can see only the taller blast walls of the United States Embassy, a 36-acre complex. The only spot of color in view is the blue tip of the minaret at the roundabout, dedicated to the prominent victim of a suicide bombing.

The blast walls are the most visible legacy of the American war, and they are not exclusive to Afghanistan: At the peak of violence in Baghdad, there was hardly a street without blast barriers or walls. Hundreds of thousands of walls, each costing close to $1,000, carved up entire neighborhoods to prevent the flow of insurgents. When the violence briefly dwindled and the government decided to lift them and let the city breathe a little, officials had no idea what to do with them. Flatbed trucks transported the walls to a desert.

But not for long. As violence in and around Baghdad has picked up again, with bombings a nearly daily occurrence, the Baghdad Operations Command has decided to use the blast walls to build a protective belt around the city. The first phase of the project, which began in February, stretches 62 miles.

In Kabul, there has been no serious effort to move the walls out — security has been getting only worse in recent years.