After Sept. 11, 2001, anxiety over terrorism engendered an intensified quest for security in the nation’s capital, creating a fortress mentality that changed the city’s visual fabric and transformed it into an uglier, palpably defensive cityscape dominated by thousands of unattractive concrete barriers and heavy concrete planters.

Fortunately, the cityscape now looks and feels much less defensive. Architects and landscape designers have created buildings, streetscapes and public open spaces that do not look or feel defensive. Many of the jersey barriers lining streets and government properties have disappeared, replaced by less conspicuous, more pedestrian-friendly vehicular impediments still capable of stopping menacing vehicles.

Well anchored, appropriately spaced elements — bollards, trees, planters, benches, trash receptacles, low retaining walls — occupy spaces between street curbs, sidewalks and buildings. A network of curving walkways edged by low retaining walls incised into the landscape makes it tough for vehicles to reach the Washington Monument.

Some building facades have been strengthened by installing window frames and glazing more resistant to shock waves generated by explosions. Other facades camouflage security measures, mostly for aesthetic reasons.

At the U.S. Patent and Trademark Office complex in Alexandria, the General Services Administration and PTO ruled out basement parking garages required by the city, citing the potential risk of a bomb-laden vehicle exploding below one of the buildings. Instead, above-ground parking garages were erected. But a multi-story, 25-foot-deep liner of offices, designed to look like rowhouses, wraps and hides the garages from public view along surrounding streets.

Of course, we haven’t abandoned the fortress mentality. In fact, many security measures that were adopted before Sept. 11 to protect against car- and truck-bomb attacks remain in place. Deadly terrorist assaults aimed at U.S. embassies abroad and the devastating truck bomb that killed 168 people at the Alfred P. Murrah Federal Building in Oklahoma City in 1995 all played a role in altering the city’s landscape.

Before Sept. 11, Pennsylvania Avenue between 15th and 17th streets bordering the north lawn of the White House, was closed to vehicular traffic. Soon thereafter, federal authorities closed E Street bordering the south lawn.

Before and after Sept. 11, jersey barriers and concrete planters were deployed around federal edifices and properties presumed to be potential terrorist targets. This included the Capitol Building, the White House, the grounds of the Washington Monument and other prominent memorials, buildings in the Federal Triangle and almost every government agency building. The security objective was always to minimize vehicular bomb threats by maximizing the stand-off distance from government facilities.

Erecting barriers wasn’t the only defensive strategy. The Pentagon’s post-Sept. 11 reconstruction included realigning Virginia Route 110, which previously passed very close to the east side of the Pentagon. This move increased the stand-off distance between the highway and the Pentagon by several hundred feet.

How truly effective are all these security measures? No one can answer that with certainty, but one thing is certain: The beauty of the nation’s capital, much compromised in the immediate wake of Sept. 11, has been substantially restored 10 years later.

Roger K. Lewis is a practicing architect and a professor emeritus of architecture at the University of Maryland.