This week, as the nation prepares to observe the 10th anniversary of 9/11, Roll Call looks back at how Capitol Hill responded to the attacks and how that day’s events changed — and didn’t change — life in Washington.

Once celebrated for its accessibility, the Capitol has been converted during the past 10 years from a symbol of an open government — and vulnerable target — to a veritable fortress.

The Oklahoma City bombing of 1995 and the Capitol shootings in 1998 initiated the change, but the Capitol complex has seen the most dramatic transformation in its history since the attacks of Sept. 11, 2001, and the ensuing anthrax attacks.

The revelation that the Capitol was a terrorist target that day — and that the facility and those inside were almost completely exposed — has sparked a seismic shift in the way security is viewed for a structure that lawmakers have fondly called the “People’s House.” The Capitol complex is no longer just a passive setting for the seat of American democracy; it is a security apparatus designed to keep federal lawmakers safe.

“9/11 took us to another dimension,” said former Sen. Trent Lott (R-Miss.), who was Minority Leader at the time of the attacks. “You tend to forget how open and free the Capitol was as late as the 1980s. When you come on the compound now, you’ve got the police that stop you, the dogs sniffing you. You go through the X-ray machines. It’s a lot tighter.”

The most noticeable renovation to the complex — and indeed the largest in its history — is the Capitol Visitor Center, an almost 600,000-square-foot,
$600 million fortified complex tucked underneath the Capitol’s East Front.

Plans for a subterranean space to screen visitors hundreds of feet from the Capitol go back decades, but it took 9/11 to thrust a somewhat unpopular and expensive plan into reality.

“That really got a boost, in a sense, from 9/11,” Senate Historian Don Ritchie said. “Congress had been very reluctant up until that point to spend a lot of federal money.”

Originally designed as a relatively simple holding zone for visitors waiting to tour the Capitol, the plans were overhauled immediately after the attacks to include underground expansion offices for the House and Senate, a blast-proof glass screening room and a state-of-the-art air-filtration system — 20 separate units, each measuring 40 feet by 12 feet by 8 feet.

About 3,000 smoke-detection devices were planned to interlink with the facility’s massive heating ventilation and air-conditioning system and a series of classified chemical and biological detection systems, largely a response to the anthrax scare.

“All of those systems were designed and strengthened, even beyond code in some instances, because of the fire marshal’s concern of a potential attack after 9/11 and anthrax,” then-Architect of the Capitol Alan Hantman said. “We had to redesign, we had to change the structural systems, we had to add stairways. Mechanical systems were completely redesigned to make sure it was the cleanest air you could possibly have.”

But the CVC is hardly the only change to the Capitol grounds’ physical appearance.

Drastic plans to construct a wall around the complex or to encase the House and Senate chambers in Plexiglas were floated but were ultimately nixed as cooler heads prevailed.

Instead, officials enacted a perimeter security plan that can essentially barricade the Capitol facilities in a large square between D streets to the north and south and Third streets to the east and west or close off individual buildings.

Gone is the traffic that once sifted between the Congressional office buildings. Commercial truck traffic around the complex has been banned outright. Officials closed C Street between Washington Avenue Southwest and First Street Southeast, and South Capitol Street and New Jersey Avenue are blocked off between C Street and Independence Avenue.

There, officers now man more than 50 security kiosks, each controlling several retractable vehicle barriers installed in the streets surrounding the Capitol. Large decontamination tents loaded with showers and fire hoses sit adjacent to many of the kiosks.

About 5,000 3.5-foot steel bollards and 1- or 2-foot reinforced gray stone walls now dot and line the campus, replacing unsightly Jersey barriers that were scattered around the buildings immediately after the attacks.

The myriad equipment would be worthless, however, without the personnel to use it.

In the six months following 9/11, the Capitol Police department was stretched thin, with many officers working 72-hour weeks. The National Guard was called in to relieve a tired force.

But lawmakers have steadily appropriated more money to invigorate the department, growing the force from about 1,200 officers at the time of the attacks to the almost 1,800 that guard the facilities today.

“That was the most rapid rise in manpower in the department,” Capitol Police union Chairman Jim Konczos said.

The department incorporated record numbers of canine units and vehicle patrols and upgraded its weapons from modest sidearms to heavy semi-automatic rifles.

Training regimens have also intensified for the force.

Konczos said the Capitol Police department runs regular drills on and off the campus site.

A 41,000-square-foot Cheltenham, Md., facility that was unveiled in 2008 houses scale mock-ups of parts of the Capitol, such as the House and Senate chambers and the Upper West Terrace.

“What’s changed most is the professionalism of the officers up here,” said Senate Sergeant-at-Arms Terrance Gainer, a former Capitol Police chief. “It’s been a sea change in the philosophy of policing. … The men and women are as much anti-terrorist as they are simply giving directions to people.”

Striking changes in security procedures were also heralded in with 9/11.

The anthrax scare sparked new mail-handling requirements, including an offsite mail facility where letters and packages are irradiated.

For lack of a siren on 9/11, officers went door-to-door, urging staffers to evacuate their offices.

But within a week of the attacks, Capitol Police handed down new emergency evacuation plans to Capitol Hill offices, and the measures have been refined ever since. Within six months of the attacks, emergency sirens were functional in the buildings.

“They became more orderly and there was a plan for each building, and I think there was better communication between the police department and the various offices,” said James Varey, Capitol Police chief at the time of the attacks.

The procedures were tested last month when a 5.8-magnitude earthquake struck the area. Sirens could be heard throughout the complex, and Congressional offices were quickly evacuated. The Capitol’s security blockades were raised, and officers surrounded the building, preventing pedestrian and vehicle traffic.

The contingency plan developed after 9/11 also had its first real test that day: The Senate convened in a pro forma session at one of several secure locations selected to house the chamber should the Capitol be uninhabitable.

Still, officials say, perhaps the most significant changes are those that the public might never know about: classified programs to thwart conventional, chemical, biological and even nuclear weapons and suicide bombers.

“There’s so much of what goes on [around] the Hill that is classified,” said former Senate Sergeant-at-Arms Bill Pickle, who served from 2003 to 2007. “The biggest changes are the ones that are not the most readily apparent, and that’s the way it should be.”