" '85 Comes Alive" at the Old Post Office on Monday night, exclaim the bright posters advertising Mayor Marion Barry's instant New Year's Eve tradition. It is a likable idea, turning Pennsylvania Avenue into a homey sort of Times Square at year's end, and it neatly underscores one of the more heartening currents of 1984: This was the year that lots of people began believing in the comeback of the "old" downtown.

Not that anyone seriously thinks downtown D.C. will ever again occupy the central place in the region's economy it once did. Indeed, 1984 was proof of this, too, as the development of commercial centers in the suburbs picked up speed. The building boom in Bethesda in suburban Maryland and the continued rush to build at Tysons Corner in Virginia are but two among many signs that Washington, like so many American cities, is fast becoming a type of multicenter city often spoken of by planners.

But fortunately, Washington is not so widely dispersed as, say, Houston; nor has its older downtown district been so thoroughly trashed as, say, Denver's. Through all the hard times central Washington has, after all, remained the symbolic heart of the nation and the center of the federal bureaucracy and the region's cultural core. These are genuine strengths. They provided backbone to optimists during the years of stagnation and decay, and optimists can now begin, perhaps tentatively, to celebrate.

Architecturally, the rebuilding of the old downtown (loosely defined as the area south of Massachuetts Avenue and east of 15th Street) has meant a decided advance in the standards that reigned when the "new" downtown (west of 15th Street) was being designed and constructed. An awful lot remains to be done, and much of the new work represents business as usual, but even so the improvement is notable. The best of the new buildings are more lively, more inventive, more sophisticated and more responsive to the city around them than was the norm not so long ago.

It is no accident that in 1984 Washington began to receive more national credit in the architectural press. True, the area still is underused and seems architecturally at war with itself. There are the cleared lots that justifiably inspire jitters and leave one wondering what happened to this or that beloved place (where is the Button Shop on 11th Street?). There are many decaying older structures that cause worry (what's to become of the Bond Building at 14th and New York?). And most of all there are those cumbersome, flat and more or less featureless new office buildings that give pause (isn't this just K Street revisited?).

But the architectural battle, so far, is at the very least a draw. Significant new pieces were added and many more were begun or approved in 1984. Take, for instance, the Daon building (so called after a Canadian development firm, and to become, sometime next year, headquarters for the Inter-American Development Bank) at 1300 New York Ave. NW. Designed by the Washington office of Skidmore, Owings & Merrill, this curving Renaissance-style building is a most improbable achievement, an enormous new structure that gives a major downtown intersection a tremendously appealing new character.

Or take the Willard Hotel at 14th Street and Pennsylvania Avenue NW, where work began in earnest on restoration and the additions designed by Hardy Holzman Pfeiffer Associates of New York. Commencement of construction on the Willard is, all by itself, the kind of consciousness-raising event that gives the old downtown a new e'clat, for the Willard is the kind of high-image building -- "something French and a few centuries old blown up for Everyman" in the apt words of Malcolm Holzman -- that gives spirited definition to the whole ceremonial western edge of the avenue. This is doubly fortunate in view of the fact that the Willard, when finished, will be locked in an everlasting face-off with the National Place-Marriott Hotel complex across 14th Street (Mitchell/Giurgola and Frank Schlesinger, architects), certainly the most prominent design dud to surface on Pennsylvania Avenue in 1984.

Any year would be improved by the completion of a Daon building and the start of a Willard restoration, and there's more -- the list of projects responsive in major ways to the city's downtown context is lengthy. It includes the completed Sears House, formerly the Apex building complex at Seventh and Pennsylvania (Hartman-Cox, design concept, taken over by Geier Brown Renfrow Architects); the ongoing Metropolitan Square complex on G Street between 15th and 14th, which despite the regrettable demolition of Rhodes Tavern is a sophisticated addition to the city (Skidmore, Owings & Merrill); and numerous buildings under way, such as the handsome new Hecht's store on G Street between 13th and 12th (Skidmore, Owings & Merrill with Melvin Mitchell), the huge Cadillac Fairview and Westminster projects on Pennsylvania Avenue (designed by Hartman-Cox and Eisenman/Robertson, respectively), each an honest effort to combine new construction with existing structures, and the sharp new-old contrast of Gallery Row on Seventh Street (Hartman-Cox). And, not least, there is an answer to the question about what is happening to the Bond Building, the subject of cliff-hanging negotiations over many years between preservationists and various developers: It is being saved and tactfully added onto (Shalom Baranes Associates).

This list is incomplete -- it would be more impressive if numerous buildings on the downtown edges or major designs approved by various agencies during the year were attached -- but even so it more than proves the point: Downtown D.C. has become an exciting laboratory of creative architectural thought, a model almost in spite of itself for other cities and for developing suburban jurisdictions.

This being my strongest and happiest impression of the architectural year just passing, I suppose I should exit with a cautionary tale. Early on a Friday night not long ago, friends and I decided to visit the new-old city center. The streets were eerily absent of life, and the restaurant we chose was closed. But if it hasn't quite happened yet downtown, I remain, like the mayor, convinced that it can. Not will happen, but can.