The Capital Children's Museum yesterday announced plans to raise $100 million so that it can relocate to L'Enfant Plaza, where it would reopen in 2008 as the National Children's Museum.

Kathy Dwyer Southern, the museum's president, was optimistic she could find the money. She said she expected the children's museum would draw 500,000 visitors a year to its new location a block off the Mall. It would be an anchor in the redevelopment of L'Enfant Plaza complex by JBG Cos. of Chevy Chase. Cesar Pelli & Associates, the architectural firm that did the new terminal at Reagan National Airport, is designing the overhaul.

The new museum will be 140,000 square feet, nearly half the size of the Holocaust Memorial Museum. The museum's board chose the L'Enfant site, after a long flirtation with the planners for the redevelopment of the Southwest waterfront. In the end, they decided on the L'Enfant location because it was easier to get to.

The first contribution toward the fundraising goal will be $24 million from the sale of the museum's 21/2 acre property on H Street NE, near Union Station. The 25-year-old museum will close its doors Labor Day and lay off two thirds of its 66 employees.

Southern hopes to maintain a level of visibility for the museum by organizing traveling exhibitions.

In an interview yesterday, Southern said the projection of a half-million visitors a year was based on an analysis done by Lord Cultural Resources, a Canadian museum planning firm.

"The projection looked at the location, the fact that it's a specialty museum, the numbers of children in the region, school groups and regular visitors," she said.

Getting to the current museum, housed in a series of buildings that date back 125 years, has meant bus or car delivery to the front door or a six-block walk from Union Station. "It is a miracle we have been able to get 150,000 to 200,000 kids and families a year," Southern said.

The Metro station at L'Enfant Plaza is a high-volume hub in the train system, with four lines using the station. The plaza also has a 16,050-space parking garage, which Southern says is the second largest in the city. When JBG approached them last fall, Southern says board members paused because of the location's lack of identity. "L'Enfant Plaza as it currently stands, does it make sense? No. But the redevelopment makes sense," she said.

Other specialty museums near the Mall have done well. The Holocaust Museum opened 11 years ago at the cost of $168 million. It was an instant success and draws 1.5 million people a year. The International Spy Museum opened two years ago this summer and charges an entrance fee, unlike most Washington museums. It has already attracted 1 million visitors.

Since it opened in mid-December, 886,000 people have visited the Steven F. Udvar-Hazy Center, the companion to the National Air and Space Museum, but fundraising has been slow. The museum still has to raise $86 million of its $311 million goal.

In the past decade children's museums, especially those that emphasize science, have been successful. The Children's Museum of Boston has 402,000 visitors a year. The Children's Museum of Indianapolis draws 1 million a year. Port Discovery in Baltimore attracts 270,000 a year.

Washington is museum-rich, but Southern thinks there is room for her effort. "There is no national icon to children in Washington, in either the memorials or monuments. There needs to be a place," she says.

Finding the money is tough but doable, she says. "I'm of the mind that more breeds more. Making a new museum is hard. You have to know your audience, study it deeply and then build to scale. We don't say, 'We will build it and they will come.' "

What her team envisions is a hands-on experience that will include a wide variety of themes and approaches. The museum plans partnerships with workers from the National Aeronautics and Space Administration, America Online and trade associations.

The architectural development team also includes Hickok Warner Cole Architects of Washington. Amaze Design of Boston heads the concept planning.