new normalcy is gradually settling in, six months after the terrorist attacks of Sept. 11.

Be prepared to wait, to be questioned, and to show identification. In every major office building in Boston - government and private - upgraded security bears in. At public buildings, there are metal detectors and a reduced number of entryways. Blazer-clad security guards, cordons, and sign-in desks confront visitors at private office buildings. Don't even think of boarding an elevator in a Boston office tower without an access card or a visitor's pass.

Many security upgrades are here for the foreseeable future. But some are relaxing as public anxiety abates and the knee-jerk response of public officials to provide quick, visible responses yields to fiscal realities and crushing overtime bills.

Despite post-attack pronouncements of coordinated responses, there is no central authority calling the shots. As a result, individual businesses and government agencies at the federal, state, and local levels are deciding, case by case, whether changes will be temporary, permanent, or even expanded.

For instance, the waterfront park at the Moakley US Courthouse in South Boston, closed since Sept. 11, is scheduled to reopen to the public around April 1. At the same time, the federal government has guaranteed an extension through May of funds to sustain the heavy security presence of 108 National Guard officers assigned to Logan International Airport. Meanwhile, state and local police are four months into plans for a dramatically stepped-up protective effort for next month's running of the Boston Marathon.

The private-sector response also varies. The observatory on the 60th floor of the John Hancock Tower is closed, permanently, for public safety reasons. But the Sky Walk, on the 50th floor of the Prudential Building, is open to visitors who produce a picture ID, sign in, and wear a lapel tag.

Trunks of cars are searched before entering the garage under the Pru, but the process has been discontinued at a garage near City Hall.

To dine at restaurants in many office buildings, patrons face the prospect of showing identification - a driver's license will suffice - before entering.

But two weeks ago at 60 State Street, the longstanding sign-in requirement was dropped for patrons of the Bay Tower, the 33rd-floor restaurant with a view of Boston Harbor. Paul Diogenes, Bay Tower general manager and chef, praised the building's security plan but said he's glad the sign-in is gone.

"Making it a hassle to come to the Bay Tower didn't help us," he said. "On Saturday nights, it was like a nightclub. I'm sure we lost a few people . . . Some people were waiting in line to sign in."

Following last fall's catastrophic events, the federal and state governments reacted by creating agencies to coordinate security deployment and antiterrorism response. To date, it's been largely an information-sharing, network-building, training effort that has helped identify potential targets and threats. In turn, that information has been used to decide the assignment of public safety personnel and restrictions on access to sensitive areas.

This is still very much a work in progress, however, and the degree of lockdown varies.

Example: In Charlestown, the Navy and National Park Service have installed a metal detector and limited access to the USS Constitution, not only a national symbol but also a commissioned warship. But there is a less visible security presence a quarter-mile away at the Bunker Hill Monument, another major attraction of the Boston National Historical Park.

Meanwhile, at venerable Faneuil Hall, which is owned by the City of Boston, security is modest.

"You can't do every building," said Michael J. Galvin, chief of basic city services. Faneuil Hall has a full-time police officer on duty, but across Congress Street, City Hall is a virtual fortress since a $200,000 security makeover after Sept. 11. There are three new metal detectors, and the capital outlay does not include the cost of 10 additional officers to bulk up what had been a 19-member security staff, Galvin said.

To some degree, money drives every decision. At every level, government budgets are swimming in red ink. Limited resources are stretched and stretched again.

"We're trying to protect those assets that can lead to the most serious problems, knowing we can't protect everything," said state Public Safety Secretary James P. Jajuga, whose office oversees the State Police and National Guard. "It's a balancing act. We understand we have limited resources, and we don't want to waste them . . . We're constantly monitoring and assessing whether we should keep people in certain situations."

There is no magic blueprint, no guidebook, or even precedent to follow. There is no way to know where - or if - terrorists have been discouraged by these measures. Everyone is making this up as they go along, using information, experience, instinct.

In some cases, though, priorities become obvious, like the Boston Marathon, now the subject of intense security planning.

And despite vows of intergovernmental cooperation, consensus has occasionally been elusive. Mayor Thomas M. Menino's administration failed in court last fall to stop shipments of liquefied natural gas through Boston Harbor until a new security plan, based on antiterrorism concerns, was devised. The tankers continue to arrive, with fireboat and helicopter escorts, traffic shutdowns on the Tobin Bridge, and increased police and fire presence at the Distrigas terminal on the Mystic River in Everett.

Merita Hopkins, Menino's corporation counsel, still believes the procedures are inadequate, and the city has commissioned a $50,000 consultant study on the subject.

The state and federal governments consider the plans sufficient. But a press release says that "due to operational and port security concerns, the Coast Guard will not discuss the specific security procedures that are in place."

At other times, politics and public policy issues are resolved on a short-term basis. The fate of the National Guard contingent at Logan is one example. Indisputably, Logan remains the chief security focus in the state. This, after all, was the staging area for terrorists who hijacked the two jets that demolished New York's World Trade Center.

The Bush administration's decision last week to extend funding for Logan's extra security at least two months past the March 31 funding deadline at least buys time.

Jajuga applauded the extension but said, "We'll redouble our efforts for a continuation through Dec. 31 . . . The Guard has done a great deal to restore public confidence at Logan."

"If they are pulled out, we'll have to backfill with State Police," he added.

The 2,200-member State Police force will be reinforced in August when more than 100 new troopers complete training.

If needed, they will supplement the 151 troopers already assigned to Logan, 68 of them deployed after Sept. 11, including an eight-member tactical unit that patrols the facility in black military garb, toting automatic weapons.

They constitute one of several new layers of protection at the airport, including periodic roadblocks, new closed-circuit television surveillance, added magnetometers and baggage scanning devices, and extra personnel who perform a series of checks, including random searches.

The result is inconvenience to travelers - a two-hour pre-flight screening process at peak times - but security won't be compromised, said Thomas Kinton, director of aviation and interim executive director of the Massachusetts Port Authority, the airport's operator.

"We will guard against backsliding," Kinton said. "I think this is here forever; it should be here forever. The expectation is that security is going to get better." It will also become less time-consuming, he predicted.

Besides airports, other priorities for extra patrols at the state level include the public water supply, telecommunications and power grids, bridges, tunnels, and ports, said Richard Swensen, whom Acting Governor Jane Swift named in December to a new post, director of the Office of Commonwealth Security.

However, Swensen, a former FBI agent who headed the Boston office, has no budget beyond his $117,000 salary. He has two staffers borrowed from other state agencies and the promise of more loaned personnel in the future.

His role is primarily to advise Swift and serve as a liaison for antiterrorism efforts at the various levels of government.

"You try to define potential targets and make them as hard as you can," said Swensen, but certainty is difficult. "It comes down to this: Is Bunker Hill more of a target than the John Hancock building? Is bioterrorism a greater threat than an attack on the Port of Boston? It depends on who the bad guy is, and what's the message he wants to deliver that day. Terrorism is a big stage, and they're looking for a spotlight."

As a result, 18 National Guard officers patrol the perimeter of the Pilgrim nuclear power plant in Plymouth, one of the most secure facilities in the state. Area residents and officials insisted on stepped-up protection to supplement Pilgrim's private security force.

In the meantime, several agencies have eased, or are in the process of relaxing, the shutdown of public recreation areas near valuable assets. Limited access is now allowed to areas around National Guard-patrolled Quabbin Reservoir in Western Massachusetts, for example. And last month, Scusset Beach State Reservation in Bourne, closed early each day since October, was reopened 24 hours a day. Restrictions were imposed at the request of the Army Corps of Engineers, which maintains the adjacent Cape Cod Canal, said Darrell Pressley of the state Department of Environmental Management.

A review has "concluded access to Scusset Beach would not significantly increase canal security risks," he said.

At the Moakley courthouse in Boston, the waterside park should reopen next month, said Timothy Bane, chief deputy US marshal. "We've got a lot of security devices in operation, but we're not going to discuss what they are," he said.

Yet at the same time, the apron around Black Falcon cruise ship terminal in South Boston remains closed, though the access issue is being evaluated, Massport spokesman Jose Juves said.

Advocates worry that public access to some recreation areas will join the long list of Sept. 11 precautions.

"We're seeing significant breaks in the Harborwalk," said Vivien Li, executive director of the Boston Harbor Association, a waterfront watchdog group. "I'm not sure we'll get them all back."

One is at the Charlestown Navy Yard. Leave the parking lot outside the facility, and the arrow points left to the USS Constitution. You can't get there from here any more, though.

Three huge concrete "keel blocks" stand behind twin "no trespassing" signs stating the obvious: This pedestrian path to Old Ironsides is history.

The warship itself was closed after the attacks but reopened two months later, albeit with reduced public viewing hours.

The sole entry point is the main gate, and concrete barriers funnel visitors to a metal detector under a white tent and a half-dozen National Park Service rangers and uniformed sailors.

"We had to empty our bags, and they checked to make sure our cellphones worked," said a visitor from Quincy as he waited to board a tour bus. "It took us five minutes, but it didn't bother me. I felt safe going on board."

In the new normalcy, patience has joined walking shoes and cameras as an essential tourist accessory at this stop on the Freedom Trail.