Ten years later that intersection – which is named Freedom Plaza – seems peaceful, with only a runner in view.

Washington Post artist Patterson Clark spent more than 10 hours over five days at Freedom Plaza this month, waiting for someone dressed in traditional Muslim clothing to walk into the frame as they had in 2001. “It never happened,” he said.

When Clark was asked by the Post to do a before-and-after photographic presentation of sites in Washington on Sept. 11, 2001 and today to show how security measures had changed, he “jumped at the opportunity.”

Clark started by combing through the Post’s digital photo files for photos of Washington landmarks and recognizable sites before and during 2001.

“An initial visit to identify the spot and decide on the proper time of day to shoot, a second visit to stand and wait for something halfway interesting to happen — and a third, fourth or fifth visit to try to improve on the results,” Clark said.

This week’s rain also postponed an “after” photo of the Pentagon— which leads the series— until the day before the anniversary.

As Clark sought to show the changing security measures in the city, he also acutely felt the changes himself. During visits to the sites, security cameras “seemed to be almost everywhere,” he said. “Spend some time standing in one spot photographing a Secret Service outpost and you can almost feel the facial-recognition software crawling across your face.”

But Clark’s finished product tells about more than just security changes. It tells about the way we grieve, with an image of the Pentagon at dawn on Sept. 12, 2001, showing a flag on the distant horizon flying at half mast, and an image of the restored building with the flag flying high.

(Arlington Cemetery)

“The ground plowed ahead of the current war casualties strikes me as a decade-old wound,” Clark said, “an ongoing aftermath of 9/11 that can’t quite heal.”

See all 13 of Clark’s before and after photos here.

The project came about with help from Todd Lindeman, Hannah Fairfield, and Wilson Andrews.