One of the best ways to begin your personal tour of the Ronald Reagan Building and International Trade Center is to stand in its commodious 14th Street plaza, looking east through the central doorway.

From this position you can see through the building all the way to 12th Street NW, more than three football fields distant. This telling, tunnel-like perspective gives you a strong sense of the building's unusual character and extraordinary potential.

However, there are other good approaches -- this is, after all, the most complex federal office building ever built, and the largest except for the Pentagon. If you start from the opposite, 12th Street side, you will move through the cupping arcade of the Ariel Rios Federal Building and then emerge from shadow to the light of a second new public plaza -- this one a vast, splendid space delineated by the architecture's powerful classic forms.

Or you can approach from the north, crossing Pennsylvania Avenue at 13th Street, and walk beside the building's eastern wall, a forceful arcaded diagonal that allows you gradually to experience the opening of the great space. In time, you also will be able to move into the space from the south by going through the currently closed archways from Constitution Avenue. From this point, downtown Washington beckons dramatically along the rising vista of 13th Street.

James Ingo Freed, chief designer in the architectural team made up of New York's Pei Cobb Freed & Partners and the Washington office of Ellerbe Becket, said [once] in a lecture that the necessity to move many people into and through the building and its public spaces was the beginning point of his design. Freed believes his resolution of these two issues -- access and circulation -- was a big reason his design triumphed over six others in a 1989 competition.

As befits its monumental surroundings, the building is dignified and impressive. It wears its size well. The walls of Indiana limestone are a crisp new take on Washington's familiar classicism. The design lacks daring, but brims with intelligence. The massive domed corner piece, in particular, is a memorable form. Sober rather than soaring, conservative rather than avant-garde, the architecture brings to a fitting conclusion the 70-year saga of the Federal Triangle, one of the largest peacetime building projects undertaken by the government.

-- Benjamin Forgey