Before the Sept. 11, 2001, terrorist attacks, visitors used to just pull up to Alexandria's Public Safety Center, hop out of their cars and enter through the front doors.

But since the attacks -- and the arrival of terror suspect Zacarias Moussaoui at the jail several months later -- checkpoints have been established, the parking lot was moved farther away, and pop-up vehicle barriers were constructed as part of an estimated $5 million security enhancement plan.

The latest security feature, at an estimated cost of $800,000, is a 700-square-foot facility referred to as the Visitors Center. Now everyone entering the facility -- which houses the police department, the jail and the sheriff's office -- is screened by magnetometers.

"It's totally different now," said Lt. James T. Robey of the sheriff's office. "You used to be able to park and walk right into the building. You can't even think about that anymore. It would be like climbing over a fence at the White House. Deputies would be on top of them."

Robey said the center, located about 140 feet from the front doors, has been two years in the making. The small brick facility, equipped with security cameras and computers, has at least two sheriff's office employees working inside who check visitors for weapons. Robey said the small building was built in Georgia and then brought to Alexandria as a cost-saving measure. The building, which arrived in three pieces, was put together like a puzzle, he said.

"Everything was bolted, locked, very secure, very tight," he said. "It's a very, very secure building."

He said the exterior is composed of Kevlar sheeting, and the glass is bulletproof inside and out.

If you are not an employee, it doesn't matter who you are -- an inmate's relative, a lawyer visiting a client, a person who wants to fill out a police report -- you must go through the center, which is staffed round-the-clock.

"We want to keep people at bay from the main building, regardless of who you are," he said. "You have to be funneled into the building."

Public Defender Melinda Douglas, who often visits the jail, said the latest security measure has not been a problem.

"Certainly it was a lot easier when you could just pull up and pop in the jail," she said, "but those days are over."

The sheriff's office has reduced traffic by placing a safety deposit box in the center where relatives of inmates can drop off money orders, Robey said. In the past, people would have to come into the building and go to the records room in the sheriff's office to drop them off.

Construction workers who maintain the facility and its grounds are now subject to criminal background checks by the sheriff's office.

"Everything has to be scrutinized," Robey said. "Everybody's suspect. Unfortunately, that is the way we have to look at it now."