Independence Hall, the cradle of the American Revolution, was temporarily closed today by the National Park Service as a security precaution at a time of heightened concern about homeland security.

The decision to shutter the historic colonial-era building was triggered when Mayor John F. Street ceremoniously reopened a block of Chestnut Street between Independence Hall and the Liberty Bell Pavilion that has been closed to traffic since the Sept. 11, 2001, terrorist attacks on the World Trade Center and the Pentagon.

The National Park Service and Homeland Security Secretary Tom Ridge had urged the mayor to keep the street closed for at least a few more months -- while the U.S. wages war with Iraq. But Street bowed to the demands of local business figures, residents and political leaders to reopen the street to all motor and foot traffic to relieve area congestion and restore commercial vitality in Center City.

The National Park Service responded by closing Independence Hall and other adjoining historic structures for at least a week while officials establish new security perimeters and metal detectors around the hall and the nearby Liberty Bell, which is open for tourists.

"While this may pose an inconvenience for visitors, we are determined to keep our visitors and the buildings safe," said Mary A. Bomar, superintendent of the national historical park. But Street said that he had been given no warning about the closing, and added that if the Park Service did not reopen the building by the end of the week, "we will consider all options, including legal action."

Area businessmen said they were thrilled that the street has been reopened and were optimistic that tourists and office workers will quickly return to nearby restaurants and stores. Critics had said the metal and concrete barriers erected did little to enhance the security of the majestic brick building, where the Declaration of Independence and U.S. Constitution were debated and signed.

"Tear this wall down," said Dennis Maher, gift shop manager at the Lights of Liberty show across the street from Independence Hall, comparing the barricades separating Chestnut Street to the Berlin Wall. Maher said business has been down as much as 50 percent since the street was closed.

For tourists, however, it was a difficult day in Philadelphia. Dennis Maxwell of Richmond arrived this morning for one day, expecting to tour Independence Hall. "I saw the Liberty Bell and took a carriage ride," he said, disappointed about the hall's closing. "It seems like some childishness, to open one and close the other."

And a group of seniors from Austin High School in Austin, Ind., found out minutes before they were to start a tour that Independence Hall was closed. "This is a symbolic building of our independence," student Joseph Kilburn said. "It's disheartening that we can't get in."

The temporary closing of Independence Hall comes at a time when the National Park Service is under mounting pressure to beef up security at many of its national parks and showcase historical sites with little in the way of additional resources.

Since the government raised its color-coded threat index to orange, or high risk, two weeks ago, the National Park Service's daily security costs have increased by $63,500, Park Service Director Fran Mainella recently told Congress. That funding comes out of the parks' strained operating budget.

The Park Service recently transferred 150 rangers from far western parks to help meet the increased requirements for protecting such national treasures as Independence Hall, the Washington Monument, the St. Louis Arch and Federal Hall and the Statue of Liberty in New York.

"When you have a limited operating budget for the national parks, having to shift more of that funding to security needs takes away from other legitimate operating needs, such as visitor interpretation programs and resource protection," sai David Barna, a spokesman for the Park Service.

On a rainy afternoon, a small cadre of supporters carrying placards with "Free Chestnut Street" on them, as well as others protesting and supporting the war in Iraq, loitered at the corners by Independence Hall, waiting for metal barriers to be removed from one of the major streets running through Center City.

Although the street in front of Independence Hall has been closed to vehicles and pedestrians, other sides of the historic building have been open to traffic. Cars have been able to park alongside the building on Fifth and Sixth streets while Chestnut Street has been closed.

A group of merchants and residents called the Coalition to Free Chestnut Street paid $18,000 for an independent security survey that found that Independence Hall was not made any safer from attack by the Chestnut Street closure -- a report that influenced Street's decision.

"We believe Independence Hall can be protected," Street said in an interview. "People come here to see Independence Hall and the Liberty Bell, and it is unfair for them to be treated this way."

Pianin reported from Washington.

Philadelphia Mayor John F. Street, center, walks down Chestnut Street in front of Independence Hall after a ceremony to reopen the street to pedestrian and vehicular traffic yesterday. Independence Hall is temporarily closed.