Few people will rue the closing of the Washington Convention Center late this month to make way for its larger, glassier replacement. Nor, on aesthetic grounds, will there be any regrets when the building gets torn down in the next year or so.

Occupying four city blocks with those relentless concrete facades and dark-tinted windows, the building is an unforgiving obstruction, a monumental mediocrity. It won't be missed.

Furthermore, the unhappy experience of living with this building for two decades could have a positive impact, forcing us by negative example to remember just how important inspired architecture is for city life and civic pride.

As it happens, the reminder is much needed at the moment. When the big bland box bites the dust, the city will be faced with an exhilarating opportunity. The demolition will create a 10-acre vacuum in a rapidly rejuvenating downtown. That the vacuum -- bounded by New York Avenue and H, Ninth and 11th streets NW -- is publicly owned gives the city the leverage needed to make sure it is filled with just the right stuff.

Ah, but what constitutes the right stuff? This is one of the big questions now being pondered by Mayor Anthony Williams and his chief planning and economic development advisers. They are committed, the planning documents say, to creating a "uniquely Washingtonian center for downtown urban life."

Unfortunately, the city is sending decidedly mixed messages about the need to make exceptional architecture a central ingredient in creating such a place.

So far, in the city's negotiations with six competing development teams about the future of the site, architecture has merited hardly a public peep. More worrisome still, high-quality architecture is not among the four evaluation criteria in the Request for Proposals issued by the city last fall. The contestants are told merely that "the experience of the developer with recognized architects will also be evaluated."

This puzzling sentence, saying so little about architectural quality and nothing about vision, is part of a category titled "Development Team Qualifications and Experience." A rather small part, it seems to me. The emphasis is on proven competence in putting together complex public-private developments. Likewise, the emphasis in the other three criteria -- development methodology, financial capability, participation by "local, small and disadvantaged" businesses -- is over- whelmingly practical.

Clearly, in and of itself, this isn't a bad thing. The ability of a development team to manage and finish a project of this size and complexity is crucial. Yet this stress on management and finance puts the cart of competence before the horse of architectural and urbanistic vision, which unquestionably should pull the whole enterprise along.

This is no small matter. These categories are weighted on a 100-point scale for those who do the selecting. "Qualifications and Experience," for example, is worth 35 points total. With that single, wimpy sentence, architecture might be worth, say, five or six points -- if that. It's ridiculous.

Oh, great architecture, that'll happen later, the city seems to be saying -- and maybe it will. But the chances would have been significantly enhanced had the city specified its ambitions in this most important official document, the one the mayor's folks will have to use in picking the winner.

To get great or even very good design, as a rule, you have to ask for it -- and make sure everybody knows you mean what you say.

Giving the mayor's planners credit, they did set the urbanistic bar pretty high in a supporting document called "Envisioning the Site." Here, they announced the intention to create a vibrant, mixed-use destination featuring residential buildings, a hotel, lots of retail and significant public uses. These would include a new central library and a performing arts complex with an exhibition hall and a couple of theaters -- one very big, for 3,000 or more patrons, and one medium-size, for 750 or so.

Most importantly, the document calls for the entire complex to be focused on a great public square of at least an acre in size -- "a beautiful and interesting landscape in which all Washingtonians can gather downtown." This could be a truly invigorating centerpiece, a city-owned public space that, unlike so many of the federally owned downtown parks, could be "actively programmed with food, entertainment and civic options."

As for architecture, well, the plan does utter an encouraging word or two about excellence in urban design and architecture. It also mentions architectural innovation with approval -- a signal, one hopes, that we don't want to end up with a nostalgic, yesterday-was-best architectural replay. Design competitions, the document suggests, could be held for key parts of the ensemble.

Concerning design, then, this document contrasts rather dramatically with the timidity of the official Request for Proposals. Yet even it is not as strong as it should be in articulating an unequivocal desire for inventive, world-class, 21st-century architecture. (This does not mean, I hasten to add, that the city ought simply to seek out one of the current architectural stars.)

Additionally, the insistence that the site be broken up into traditional urban blocks -- and in particular, that both 10th and I streets NW be reopened -- could exercise a significant drag on architectural and urban design innovation.

Certainly, "to knit this important four-block area back into the fabric of the city" is an important goal. But simply to divide this acreage into conventional urban blocks may not be the most imaginative, spatially compelling way to reestablish historic vistas and to tie this development to the surrounding city.

Here, the lesson is: If you want extraordinary results you have to ask for them, and then sort of get out of the way. (You can always come back and say, "Hey, wait a minute.") Imaginative architects, to be their best, need room to play, to experiment with spatial possibilities below, on and above ground. The extraordinary sequence of public spaces that Daniel Libeskind imagined in his competition-winning design for New York's World Trade Center site is a pertinent case in point.

One additional architectural matter is worrisome. This is the call for a new central public library/media and technology center. The bothersome part is that the central public library we already have is housed in one of the city's few very fine modernist buildings of the second half of the 20th century -- Ludwig Mies van der Rohe's Martin Luther King Jr. Library at Ninth and G streets NW.

The Mies building is not cuddly. It's not entertaining. Aesthetically, it is the antithesis of both traditional libraries of yore and the wiggles and squiggles of the contemporary avant-garde. But it pleases both eye and mind with its cool rationalism and rigorous symmetry.

Furthermore, the building was designed as a library and, I can attest from many years of personal use, it works very well for the purpose. The emphasis of the architecture is on public usefulness. To sit with a book in any one of its stark but light-filled reading rooms is a serious treat.

For sure, like the District's library system as a whole, this headquarters building has been poorly maintained. But it needs help, not abandonment -- it's a spacious structure that could accommodate new infrastructure and technological systems. To bail out on such a building is a bad idea in general and, not incidentally, a terrible way to demonstrate a serious interest in quality architecture.

There is, of course, plenty of time. My hope is that the complaints in this column are proven wrong and that the city lives up to its best words, for this extraordinary downtown site clearly deserves the best architecture we can give.

This watercolor commissioned by the city envisions a vibrant public square.Planners are calling for a library on the site of old Convention Center despite the proximity of Mies van der Rohe's Martin Luther King Jr. Library, above.The old Convention Center, all solid walls and tinted glass, is not likely to be missed.