One of the unhappy temptations of walking around downtown Washington -- west side, east side, take your pick -- is to throw up your hands in despair, or disgust.

The office building boom that has been going on for nearly two decades, with but a few economic interruptions, has produced so many unlovely, unimaginative, stamped-out boxes, collectively and separately so destructive of the social and physical fabric of the city, that to react otherwise seems almost silly.

And yet there is much to be thankful for. The city still retains much of its awesome beauty. The streets and boulevards of L'Enfant's noble plan for the place, fleshed out over time by full-grown trees, still proclaim the beneficent power of intelligence, mediating even the most banal of the new superblocks. And here and there one comes upon fully preserved fragments of the older city and heartening signs that architectural intelligence and imagination have not vanished altogether.

Most of the better new, large-scale projects in the city -- completed, under construction or in final design stages -- result from an alliance between preservationists and architects, and deal explicitly with the problem of recycling these older fragments, which, not without conscious irony, we value more highly the rarer they become.

Preservationists and architects (not to mention developers) do not always see eye to eye on the issue. The alliance is inherently an uneasy one. At one extreme a preservationist would argue that nothing short of complete restoration of the old structures, inside and out, will do. At the other an architect would exclaim, "Down with the old, up with the new!"

With increasing frequency, driven by necessity (in the form of the city's preservation law), economics (in the form of federal tax incentives for preservation) and conscience (in the form of parallel, though hardly identical, ideological commitments), they meet somewhere in the middle.

The basic tactic is simple: mass new construction behind an ensemble of older buildings. In practice this does not often lead to the best of all possible worlds. Land is sold and bought on the basis of density allowed by the city's zoning map. Frequently the result is a tremendous discrepancy in scale, with the new structure towering ominously over the old.

But it is too easy to attack the idea as an unholy compromise, a sort of instant "fac,adism" that serves neither preservation nor architecture with distinction. This is because in terms of urban design the benefits, both potential and actual, are so numerous.

Fortunately, by now, this is no longer just a theoretical proposition. The very existence of "Red Lion Row," a collection of low 19th-century buildings facing Pennsylvania Avenue between 20th and 21st streets NW, is but the most recent example in a lengthening list of projects that demonstrate the point. Today this block is a sorry-looking ensemble -- a Potemkin's Village of building fronts propped up by steel supports -- but it takes no great imagination to picture a worse spectacle: no buildings at all and a huge construction ditch foretelling a massive office building.

This is precisely what would have occurred had George Washington University been allowed to go forward with its initial plans. Karen Gordon, the president of Don't Tear It Down, who even as an undergraduate seven years ago at the university led the fight to save the buildings, says somewhat ruefully, "We don't usually advocate fac,ade preservation, but often it's the best deal we can get."

Still, Gordon is right when she claims the benefits substantially outweigh the penalties. The 10-story office building (designed by John Carl Warnecke Associates in collaboration with Hellmuth, Obata and Kassabaum), with its long horizontal courses of reflective windows, will make a rather insensitive background for the 19th-century fac,ades, which are to be filled in with new construction to their original depth. But at street level the ensemble will continue to exert its highly inflected allure, and the glass-covered retail galleries between the old and new structures will make a lively contribution to the cityscape.

Warnecke is repeating here the pattern he set back in the early 1960s when, with the active support of his friend, President John F. Kennedy, he devised the program to save the beautiful rows of old, low buildings bordering Lafayette Square. This was an important victory for the city and a foreward-looking solution to the problem that still vexes us today, but it is disappointing to note no significant conceptual advance between that project and the new one for GWU.

Recent projects by other firms in Washington have added considerably to the range of choices. One of the more interesting and successful of the new responses is a narrow, five-story office building at 1915 I St. NW designed by a Washington firm, Kerns Group Architects, headed by Thomas Kerns. What these young architects did was quite straightforward: They proposed to the developer that, instead of demolishing the building and thereby losing its circumspect blend of brick-and-stone Gothic details, he simply build to the allowable density by adding four floors at the top.

Although certain details of the design are too clever by half (changing from red to blond brick to mark a new entrance to a below-ground restaurant, for instance), the basic idea is apt: Each of the four new floors, set back a few feet from the one below, precisely echoes the high-stepped top of the original structure. It is perhaps a small idea, but the project itself is admirably small, and it adds a grace note of wit to the streetscape. (The size of the project itself is worthy of emulation, a welcome pause in the megabucks-from-megablocks syndrome.)

A more problematic entry is the new office building on the northeast corner of 18th and F streets NW designed by Skidmore, Owings and Merrill (David Childs, partner in charge). Here a rather attractive, vaguely Art Deco new building -- dark, narrow, horizontal window bands alternating with seductive blocks of polished pink granite -- steps back politely from four lower, Victorian-style brick buildings at the corner.

Although sound urban design arguments apply to this building -- in scale, at least, it curtsies to the street and to history, and in materials it bows to a handsome late Federal mansion across the street -- the net effect is rather like a parfait with too much artificial sweetener. Three of the four "preserved" Victorian structures are, basically, brand-new buildings, and all of the gray-painted trim is new. The building may improve with age, but most likely the confusion it sows as to what is real and what isn't will not disappear.

This short list is by no means exhaustive. A prominent example of fac,ade preservation is Metropolitan Square at 15th and G streets NW (also designed by Skidmore, Owings and Merrill), where the imposing Beaux-Arts fronts of the Keith-Albee and National Metropolitan Bank buildings are being skillfully folded into a massive concrete-and-glass office-retail structure. The Martin & Jones design for an office tower behind a row of attractive brownstone houses in the 1700 block of N Street NW, which in fact preserves much more than merely the fac,ades of the old buildings, does justice to one of the more enchanting (and complete) 19th-century blocks in the whole of downtown. David Schwarz of Architectural Services is putting the final touches on an imaginative design to build a large structure behind a handsome row of Victorian brick buildings at 19th and N streets NW.

Each of these projects deserves fuller consideration but taken together, at the very least, they provide relief from the mindless mediocre march. At best they offer physical evidence of even better things to come.