Washington is a city of beautiful big apartment buildings but the best of them are old--the older, the better, it is almost fair to say.

The newer ones, mostly built in the last 20 years, tend to be basic blocks, built according to a formula determined by zoning ordinances, height restrictions, building regulations, axioms of the real estate trade, deficiencies of the construction industry and, above all, developer economics. It was a formula that discouraged whimsy, ornament, craftsmanship, spaciousness, delight.

There are three new apartment buildings in the city that challenge this formula in different ways, although, interestingly, as apartment buildings they are economic accidents. Each began as a condominium and switched to rental only after the condo market collapsed. As architect Arthur Cotton Moore, who designed one of the buildings, points out, "The reason why apartment buildings aren't being built today is because it is a good way to go broke."

The three projects are Moore's Logan Park, a 112-unit building at 13th and N streets NW, near Logan Circle; the Mondrian, a 128-unit sequence of structures nearby at 12th and N streets NW, designed by Wanchul Lee, and the Barclay House, a narrow 27-unit building at 25th and K streets NW, designed by Martin & Jones.

These buildings are exceedingly dissimilar in looks if not in use. In itself this is a tribute to the conscientiousness and skill of the architects.

The Barclay House is a memorable, Mannerist essay, a restless, self-conscious tour de force that somehow manages to stand on that K Street corner as if it had been there for years--a contradictory feat. A first glance (from, say, the window of a passing car) nearly convinces the viewer that this is an old building that has been submitted to surgery.

The principal, striking feature of the building is the carved-out appearance of its two main fac,ades facing K and 25th streets, respectively. Further reflection and closer inspection reveal the architects' complex intentions. The fac,ades are worked in four distinct planes: an innermost layer of blond brick, an emphatic grid of exposed-concrete structural columns painted gray, a smooth plane of red brick (with sash windows set flush to the wall) and projecting bays of the same blond brick.

Details have been carefully considered to emphasize the visual and symbolic differences between these levels. It is as if the architects were conducting a lecture, insisting that we see just how the building was put together and, more importantly, that we become acutely aware of the particular, peculiar stresses of the present moment in architecture. The broken arch of the entranceway is, in itself, a fragmented historical quote that makes it one of the snappier, more intelligent apartment entranceways in the city.

"We treated it the building almost as we would have treated a studio problem in architecture school," says David Jones, a partner (with Guy Martin) in the Martin & Jones firm. The basic idea, they say, was to express two buildings in one: the red wall and exposed columns signifying "the dumb apartment house" and "the neutral in-fill of the city," while the exterior blond-brick fac,ade and the rusticated base refer to a fancier, richer, more civilized architectural experience.

This is pushing theory pretty hard, but it works. I can think of no Washington building that better encapsulates today's uneasy range of choices among technology, economics and esthetics, among older styles, Modernism and some still-evolving new dimension. At the same time, this disturbing design comfortably fits its neighborhood of older, somewhat plainer, apartment houses.

Logan Park is a massive, vociferous, ungainly corner building that bears Arthur Cotton Moore's inimitable stamp from sloping, skylit roof to canted corner to giant, shrewdly modulated bays and an exclamatory polychrome pattern of half-arches.

Rather than try to hide or neutralize the unavoidable issue of size and scale, the architect clearly decided to push it to the limit. As a result, the building is an outsized commentary on some of the outlandish proportions of nearby Victorian residences. This is not entirely a happy result--deficiencies such as an uneven row of windows at the top floor and a service penthouse with a cliche'd sloping metal roof are written very large, indeed--but it is a strong statement in a place that can take it.

The building's most endearing feature, in fact, is its oddness, its idiosyncracy. The dialogue it establishes with its very mixed urban surround is curiously provocative. The heavy pattern of yellowish against deep burgundy bricks, for instance, echoes patterns in smaller Victorian structures in the neighborhood while simultaneously weaving together the principal colors of the mostly undistinguished nearby apartment blocks.

As usual with Moore's projects, there are some nice urban design touches, such as the row of apartments and offices on the ground floor opening directly onto the streets and the rooftop recreation area with its cast-iron balustrade, which, like so many of the amenities in each of these projects, was not originally permitted by existing D.C. regulations.

Wanchul Lee's buildings down the street, at 12th and N, are as quiet as Moore's Logan Park is loud. This fits their relatively background location. The Mondrian, as the project is called, consists of three separate buildings--two nine-story blocks on N Street and a row of four-story units facing 12th--with a common entrance and unprepossessing fac,ades of red bricks with concrete columns and lintels.

The design of the Mondrian is curiously unrelated to the right-angled geometries of the paintings by the Dutch Modernist master, but the name does serve, in a general way, to announce the architect's low-key Modernist approach: "I didn't start with a design style in mind," Lee says, "but with the idea of building a place for people to live in. My feeling is if you do that right, then the building will automatically be interesting."

Lee's thoughtfulness yields dividends. He had more room to work with (nearly an acre of ground) than the other architects considered here and he made good use of it. The row of low-rise units, cleverly angled to catch the sun, complements the existing fabric along 12th Street, while the high-rise blocks complete an urban wall along N Street. An attractive interior courtyard, partly visible from the street, unites the three buildings.

As different as these three projects are, they share one unfortunate quality: wretched workmanship. Sloppy detailing prevails. The brickwork in places is as bad as can be imagined and some of the concrete pours could have been done better by dump trucks. Despite this, the buildings are thoughtfully designed places to live and creative additions to the cityscape. And the Barclay House, in particular, is something extra-special: as good a building as the city has seen in a long time. CAPTION: Picture 1, Moore's Logan Park. Picture 2, Martin & Jones' Barclay House. Picture 3, Lee's Mondrian. Photo 1 copyright (c) 1983 by Maxwell Mackenzie; Photo 2 copyright (c) by Harlan Hambright