Notoriety is fleeting at the Alexandria jail. Convicted spy Robert Hanssen was bumped from his cell to smaller, more confining quarters on a different floor to make way for suspected terrorist Zacarias Moussaoui.

Moussaoui, meanwhile, the first person to face U.S. criminal charges in the Sept. 11 attacks, has been settling into Hanssen's old digs, where he spends 23 hours a day alone, quietly reading the Koran and praying on the floor on a blanket. He rarely uses the jail-issued television, preferring to read and pray.

"He is being very well managed, very well supervised," said Alexandria's longtime sheriff, James H. Dunning, who has never had an escape, suicide or fatality at the jail.

Dunning and his deputies have become adept at juggling a who's who of sociopathic killers, drug kingpins and other high-risk inmates at the 15-year-old Alexandria Detention Center. Many high-profile suspects have slept here: CIA spies Aldrich Ames and Harold James Nicholson. Former United Way chief William Aramony. Political maverick Lyndon H. LaRouche Jr. Drug kingpin Rayful Edmond III. Suspected child killer Gregory D. Murphy.

Through a special contract with the U.S. Marshals Service, the local jail houses federal inmates -- including 151 yesterday. In 1997, the jail had three spy suspects at once -- Nicholson, Robert C. Kim and Earl E. Pitts. Housed near one another, the three men apparently became cordial and were sometimes seen playing cards together in a day room.

But Dunning says Moussaoui has no such interaction. He is locked up in "administrative segregation" and is treated no differently from "anyone we view as extremely dangerous." About a dozen others arrested as part of the terrorism investigation -- including Agus Budiman and Mohamed Abdi -- are being held in the state-of-the-art eight-story jail, which was built in 1987 without bars.

Moussaoui, 33, is charged with conspiring with Osama bin Laden and the 19 men who hijacked and crashed four airliners into the Pentagon, the World Trade Center and a Pennsylvania field.

He spends 23 hours a day alone inside his 80-square-foot cell, which has the standard stainless steel toilet and sink, plus a concrete slab with a thin mattress. Natural light streams in through two vertical slit windows in his cell, about six miles from the Pentagon, where 189 people were killed in the attacks. The five cells around him have been kept empty for his safety and others', and Moussaoui has access to the common area in the cluster.

There is no privacy; he is constantly watched on a closed-circuit security camera. He has not given anyone any trouble, authorities say.

One hour each day, Moussaoui, a French citizen of Moroccan heritage, is escorted from his cell for a shower and exercise. When he is taken to federal court -- just two blocks away -- the entire jail is locked down.

"He does everything alone," Dunning said.

Moussaoui is not allowed to mingle with other inmates or have his full beard trimmed in the jail barbershop, where an old-fashioned red, white and blue light pole rotates outside the door. He eats by himself.

Like other vegetarian inmates, Moussaoui receives a rotating menu approved by a dietitian and prepared in the jail kitchen. Breakfast on a Monday is sometimes grits, eggs and coffee cake. A typical Thursday dinner: pinto beans, seasoned rice, corn bread and a cookie.

Moussaoui's presence at the jail has not disrupted normal operations, according to lawyers who visit clients there.

"The Alexandria jail is a very professionally run operation," said Melinda Douglas, the city public defender. "Everything is going along as normal. I'm sure they're challenged, but I haven't noticed any concern, fear or anxiety on the part of incarcerated clients."

Although life appears normal inside the jail, it is anything but outside.

Before Moussaoui's arrival, chain-link fences topped with barbed wire suddenly sprang up around the perimeter of the rust-orange brick Public Safety Center, which also houses the city's police department and magistrate's office. Jersey barriers line the entrance, parallel to the nearby Capital Beltway. All visitors to the Public Safety Center on Mill Road must stop at a checkpoint manned by deputies, show their identification and state their business.

Defense lawyer Jonathan Shapiro has experienced the enhanced security firsthand. As he tells it, when he approached the security checkpoint, the deputy in charge recognized him because he has visited so many times to see clients.

"Hi, Mr. Shapiro. I need to see some ID," the deputy said.

But when Shapiro confessed he had forgotten his driver's license, the deputy sent him away without letting him in.

Many of the security changes have been in the works for two years but were expedited after Sept. 11, Dunning said.

The jail is so full of high-security people now that Shapiro's current espionage client -- retired Air Force Master Sgt. Brian Regan -- can't even get in. Although he is slated to go to trial in March and needs to consult regularly with his attorneys, Regan has been shunted out to Orange, Va., because the jail is too full.

The jail was built for 343 inmates but now holds about 400. Dunning says the jail easily handles the overflow by double-bunking some inmates.

The challenge, said the sheriff, is juggling inmates while maintaining the lowest possible level of tension. "You don't want an inmate with aggressive tendencies to be around someone who might be vulnerable," said Dunning, a Democrat who was first elected to his post 16 years ago.

Deputies strive to make the inmates feel they are being treated fairly. Whether they are in jail for shoplifting or spying, everyone is accorded the same courtesy title, including "Mr. Moussaoui."

Not everyone is so pleased with the jail's handling of post-Sept. 11 detainees. The attorney for Budiman, the Indonesian man who is being held in isolation while authorities explore his past contacts with the Sept. 11 hijackers, filed a motion yesterday complaining of his client's treatment.

The lawyer, Bill Moffitt, alleges that Budiman has been held in isolation 22 hours a day and is allowed to make phone calls only from 1 to 3 a.m. Budiman, who is charged with identification document fraud, has also had trouble breathing and been treated for stress, Moffitt said.

"It's ridiculous. . . . He's been reduced to giving up his food to other inmates to get word to me" through them, said Moffitt, who is seeking his client's release on bond.

Dunning says inmates, including the most notorious ones, are moved around, and will continue to be, as security needs are reassessed.

"This is not a temporary situation," said Dunning. "These kinds of cases -- there will be more."

In fact, the American Taliban, John Walker Lindh, will be tried in Alexandria, and speculation is already rampant that he will join the crowd at the city jail.

Visitors must show ID and state their business before visiting the Public Safety Center.Deputy Andrea Hurley checks a visitor's ID, and Dwayne Morris checks the car outside the Public Safety Center.