The National World War II Memorial opened to the public today after nearly two decades of debate and anticipation, assuming a central place among Washington's defining landmarks.

The chain-link fences surrounding the $172 million project began to come down early this morning, and visitors were allowed to enter the 7.4-acre site shortly before 9:30 a.m. -- a month before the memorial is to be officially dedicated Memorial Day weekend.

"I've been looking forward to seeing this for years," said George Griffenhagen, 79, of Vienna, Va., who served in World War II with the Army's 20th Combat Engineers and landed at Normandy in 1944.

As he filed into the memorial with several hundred other visitors, he said its grandeur recalled one of his most vivid memories of the war: when, approaching Normandy, "we saw thousands of ships, and every ship had a barrage balloon over it, and it was an amazing, awesome sight." The World War II memorial, Griffenhagen said, "reminds me of that. It's breathtaking."

The opening marked the culmination of a campaign that began in 1987, when legislation to establish the memorial was introduced in Congress. Arguments about its location and design -- in Congress, in public hearings and in federal court -- delayed the start of construction until 2001. The project is virtually completed, although some landscaping work and the installation of several sculpted relief panels will continue after today's opening.

Indeed, some workers were continuing to put finishing touches on the memorial even as tourists filed in.

Officials in charge of the work said they were leaving some sections of fencing in place to protect some of the newly laid sod.

The May 29 dedication ceremony and other Memorial Day weekend events are expected to draw about 800,000 people to the Mall, according to the National Park Service. But some groups have booked trips to the memorial to beat the dedication crowds.

Others, such as Cleora Karr, 76, of Marcellus, Mich., just happened to be visiting Washington today and got in line with her daughter to enter the memorial.

"I didn't expect the immensity of it," she said. "It's so huge. I didn't know it was going to be anything nearly this big." She said she planned to return to the memorial with her husband, Charles Karr, a Navy veteran of World War II who was in Annapolis this morning.

Officials said they wanted to open the memorial before the dedication to allow as many visits as possible by World War II veterans -- who are dying at a rate of about 1,100 a day, according to the American Battle Monuments Commission, the project's sponsor. Large tour groups of veterans will begin filing into the memorial early next week.

"When I asked some guys about going to the [dedication], they said they didn't want to do that because there'd be too many people," said Sandy Hart, who about a year ago began organizing a tour of the memorial for veterans living near her in western Kentucky. "So I set something up for the beginning of May and I thought, 'I'll see if I can get 10 or 12 people.' "

She got a lot more than that -- about 1,000 people heard about the trip and told her they wanted to go. Deaths, strokes, broken hips and other complications have whittled the numbers down slightly, she said, to about 800. More than half of them are veterans of the war, she said, and they will board 17 buses and arrive in Washington on Monday.

"I'm glad that I'm going to get to see it, because there are a lot of us that won't be able to," said Dan Garrott, 81, of Mayfield, Ky., who won a Silver Star while serving with the 30th Infantry Division in Europe from 1942 to 1945. "For me it'll be a chance to mix with some more veterans and swap a few stories -- sort of a memory trip, I guess."

In the past several weeks, the memorial has established itself as one of Washington's most photographed landmarks, with tourists lining up in front of the chain-link fences to get shots of it in its nearly completed state. Its prominent location, squarely between the Lincoln Memorial and the Washington Monument, virtually ensures that it will be among the city's most visited attractions.

That was precisely the intention of the federal design panels that approved the memorial's location in 1995. Given that the memorials to veterans of the Vietnam and Korean wars occupy about 2 1/2 acres each, panel members agreed that the best way to make the World War II memorial commensurate with its significance to American history was to give it a larger site at the heart of the Mall.

Planners also were guided by the idea that just as the Washington Monument represented the 18th century and the Lincoln Memorial the 19th, the World War II project belonged on the Mall's central axis as the symbol of the defining event of 20th-century America.

But the proposed site sparked opposition from those who believed that the structure would corrupt the open vistas on the Mall and obstruct pedestrian access between the Lincoln Memorial and the Washington Monument.

Judy Scott Feldman led a group that tried to block construction of the memorial, arguing that its location and design were inappropriate and that federal panels had violated procedural regulations in approving it. The group filed suit in federal court, but Congress responded in 2001 by voting to shield the project from judicial review and expedite construction.

Feldman, whose group is trying to prevent other construction projects on the Mall, said a recent visit to the completed memorial persuaded her that her concerns were justified. "It's pretty much as I thought it would be -- kind of split in two, big and gray, and right there in between Lincoln and Washington," she said. "It very much is a presence that breaks up the continuity of that space."

Hugh Hardy, a New York architect who was a member of the memorial's design jury, said he believes that it does not subtract in any way from the power of the two landmarks on either side. At a Washington symposium discussing the memorial last week, Hardy said the new structure complements its surroundings.

"I can't believe when you go there you won't be more aware of what the Mall is, more aware of the two great monuments that this is so inextricably linked with," Hardy said.

The memorial features side entrances to the north and south and a ceremonial entrance on 17th Street. The walls flanking the ceremonial entrance will feature 24 bronze bas-relief panels, some of which will be installed after the dedication.

The main plaza of the memorial is an oval defined at its north and south edges by two 43-foot arches, representing the war's Atlantic and Pacific theaters. Fifty-six pillars form the perimeter of the oval, representing the states, territories and the District of Columbia at the time of the war. Each pillar is adorned with two sculpted bronze wreaths.

Inside the plaza, small fountains sit at the bases of the two arches. A wall of 4,000 gold stars -- each representing 100 U.S. deaths in the war -- is surrounded by waterfalls on each side. The Rainbow Pool, which has occupied the site since the 1920s, has been restored and features a series of jets designed to produce a spray that looks like a rainbow when sunlight hits it at a certain angle.

More than two-thirds of the memorial consists of grass, plantings and water. A double row of elm trees lines the memorial to the north and south. A circular garden of about 38 feet in diameter sits in the site's northwest corner and is enclosed by a two-foot-high stone wall. Called the "Circle of Remembrance," the garden includes a seating area with wooden benches.

Like the Mall's other monuments, the memorial will be open 24 hours a day. Park Service rangers will be on site seven days a week from 9:30 a.m. to 8 p.m. The Park Service is discouraging visitors from leaving mementos. "There is no place for keeping them, and sadly, if people leave flowers, they'll likely just be thrown away," said Bill Line, a spokesman for the agency.

Parking on the site is limited to five disabled parking spaces accessible from southbound 17th Street, and there is a driveway for tour buses to pick up and drop off passengers. The nearest Metrorail stop is the Smithsonian station, a little over a mile away. Tourmobile will designate a memorial stop for its open-sided trams on Constitution Avenue between 17th and 18th streets, according to the National Park Service.

An information center will open today on the south side of the memorial, where tourists can ask Park Service employees to search the World War II Registry, a database of individuals who served in the war effort either in the military abroad or as a civilian at home. People can add a name to the registry by visiting the American Battle Monuments Commission Web site at www.wwii memorial.com.

Tourism officials said they will be able to fully judge the impact of the memorial after this summer's "America Celebrates the Greatest Generation" tribute, which will run from the dedication of the memorial through Labor Day and feature more than 140 World War II-themed events sponsored by more than 80 cultural institutions.

Victoria Isley, a spokeswoman for Washington D.C. Convention and Tourism Corp., said she expects that the World War II events will attract about 1 million more people to Washington than would normally visit during the summer, boosting the traditional seasonal figure of 5 million visitors to about 6 million.