The reasons for closing the 900 block of G Street NW to traffic 25 years ago sounded fabulous. So did the reasons for reopening it yesterday.

In fact, they were identical.

"It helps bring fresh life back to this important block," Richard Bradley, executive director of the Downtown D.C. Business Improvement District, said yesterday.

"We are here to celebrate the resurgence of a great city," said Mayor Anthony A. Williams (D), standing at a microphone next to the Martin Luther King Jr. Memorial Library before a crowd of downtown boosters.

In 1977--when a pedestrian plaza was dedicated there--Mayor Walter E. Washington also stood at a microphone before a crowd of downtown boosters. His exact words have been lost in the mists of time, but his administration left behind a document describing the project.

"It will bring new life into downtown--life more nearly round-the-clock," reads a brochure shelved in the library's Washingtoniana Room. "It should make the downtown area more attractive to shoppers, increasing retail sales and improving property values."

The District's planners have now covered all bets for what to do with G Street. And the best minds in urban design applaud them--as they did last time around.

What happened in the past 25 years is that the "pedestrian mall" concept has been debunked. Across the country, streets were closed and replaced with fountains, trees and benches to lure shoppers from suburban malls.

Most pedestrian malls instead attracted loiterers and skateboarders, becoming somewhat frightening, which is what happened to the 900 block of G Street.

"In place after place, they proved pretty disastrous, because Americans . . . are wedded to their cars," said Richard Longstreth, professor of American studies at George Washington University. "If they can't see it from their car, they don't come."

The trees and flowers on G Street were lovely, but the fountains were soon neglected and turned into planters. Some people felt uncomfortable crossing the plaza to reach the library, and others who might have driven past never knew the library was there, said Molly Raphael, the city's director of public libraries.

"We are not making room for cars," said Del. Eleanor Holmes Norton (D-D.C.). "We're getting rid of blight and rats, and this is the only way to do it."

It cost $1.2 million to tear out Hubert H. Humphrey Plaza, as it was called, with the federal government paying 80 percent. It cost $3 million two years ago to reopen the 700 and 800 blocks of F Street NW and the adjoining 500 block of Eighth Street. Creating both pedestrian malls had cost $6.3 million.

Reopening blocks has a special significance in Washington, where the street grid, designed by Charles L'Enfant, is a masterpiece listed on the National Register of Historic Places. To close a street means "the formative character of space in the city is forever altered," Longstreth said.

Nowadays, streets are closed with developers or terrorists in mind. The old convention center at 10th and H streets NW, the new one under construction at Mount Vernon Square and MCI Center at Seventh and F streets NW all forced the closing of blocks. Pennsylvania Avenue in front of the White House was closed for security reasons.

At one time on the 900 block of G Street, you could go bowling, eat a meal, purchase a piano, have a watch repaired, try on a dress, hire a lawyer, buy liquor, order flowers, fix a typewriter. Most of that was gone by the time the library, designed by Mies van der Rohe, opened in 1972.

The block has new granite curbs and 26 new parking meters. With one lane in each direction, it is not meant for commuters but to improve circulation in the neighborhood.

The first people to drive it in 25 years were Gayle and Bill Bauer of Bethesda, heading west in a green Toyota at 11:56 a.m. They had no grand thoughts of urban design in mind. They were just trying to find a convenient route from the National Gallery of Art on the Mall to the Museum of Women in the Arts on New York Avenue NW.

"I was delighted," Gayle Bauer said, waiting at the red light on G at 10th Street. "I was surprised we could get through."

CAPTION: Traffic makes its way down the 900 block of G Street NW. It had been converted into a pedestrian mall in 1974.

CAPTION: D.C. Council member Charlene Drew Jarvis, left, Del. Eleanor Holmes Norton, council member Jack Evans and Mayor Anthony Williams attend the reopening.