"The hardest part of this job," said David M. Schwarz, architect of the new Penn building on Pennsylvania Avenue SE, "was to please everybody. The way it turned out, the front was for the Art Deco Society, the back was for the Capitol Hill Restoration Society and the middle was for me."

Schwarz, obviously, is not a purist of the old school. At 35, he has been making a splash in the Washington architecture pool for just five years. His career has been distinguished by stylistic eclecticism and aided by his ability to work within the city's nettlesome but necessary set of design constraints.

But even for Schwarz the Penn building is notable for stylistic diversity, a little complex divided, like all of Caesar's Gaul, into three distinct parts.

The office-retail Pennsylvania Avenue segment, in deference to the 1930s movie house that formerly occupied the site, is a deft '80s reminder of the Deco decade. The residential rear portion, facing C Street SE, takes pieces from the Victorian Era puzzle that is residential Capitol Hill and says, straightforwardly, "People live here." And then there is Schwarz's middle, a tiered triangular space open to the sky, defined by walls of Mediterranean whiteness. The most prominent of these walls -- the building's most original feature, in fact -- is a stark grid, four stories high.

This is an odd assortment of personalities but, perhaps not so oddly, they work well together, for they are parts of as sophisticated and refreshing an architectural effort as the city has seen in recent years. The main reason, other than Schwarz's superior design skills (and the abilities of his young colleagues in his eight-year-old firm, Architectural Services), is quite simple: When on the street, one perceives the parts separately.

The south fac,ade is just a wonderful bit of sleight of hand, an almost all-new structure that, with no more than a few old pieces (the theater marquee, the neon sign, several limestone ornamental details in the Deco-Greco mode), conveys something of the exuberant romance of commercial architecture in the '30s. Of course Schwarz is playing with our memories here: His new building is much more emphatic than the original Penn Theatre.

This is because of the color -- three floors of bright blue tiles (with accents in red and white) atop a conventional limestone base -- and the way in which, with carefully calculated setbacks and mirror-image wings, he celebrates the central marquee. There are a couple of jarring details (the red trim of the shop windows is too bright and the rounded store entrances are too cute), but basically this is a case in which the new is a lot better than the old.

It may be that the new Penn building represents the '30s as we like to think of them in the '80s -- the Depression Era minus the Depression -- but it sure is a look-at-me structure in the right place. It lights up a commercial block that was sorely in need of such attention, and it makes one aware that there are quite a few places in the city where, as Robert Venturi once pungently said, less is a bore. Nothing similar can be said about the C Street fac,ade, which, if not outright boring, is simply not so distinguished a piece of work. Oh, it's clever enough -- Schwarz points out correctly that he has built a 35-unit apartment building with a row house look -- and it more or less suits the Capitol Hill pattern of brick bay fronts with stone trim. But its detailing has very little of the texture or substance, and none of the color, that distinguishes the best Capitol Hill places. "By now I can do this sort of thing," he says, "with my hands behind my back."

There is, however, one feature of the residential complex that merits special attention, and certainly will get it from pedestrians once they discover its existence. This is the covered pathway on the ground floor that leads to the open courtyard between the C Street residences and the avenue shops. The public circulation system as a whole is superb: Schwarz and his helpmates had the good sense to recognize a potential shortcut when they saw it (a diagonal line running through the center of the site) and they capitalized on the opportunity by providing a walk-through lobby on Pennsylvania Avenue. As a result, when finishing touches are over with in a few days, one will be able to cut through the project on the way to or from Eastern Market. This is the kind of interesting pathway people in cities almost always will take when given the chance; not coincidentally, it's also good for business. Yet another plus is that, though the theater marquee no longer leads to a movie palace, it still admirably performs its old alluring function of saying, hey, come on in.

Architecturally, the courtyard is a bold stroke, a radical switch from history-quoting styles to the world of the unornamented grid. The transformation is somewhat surreal, emphasized as it is by the exaggerated statement of the all-white screen wall. Schwarz points out that this remarkable wall performs a number of functions: Although it looks free-standing, it actually provides structural support for the residential building; facing south, it also serves as a sun screen; and it nicely frames views from the apartment balconies.

It does all of these things -- but one gets the impression that, mainly, it was just something Schwarz wanted to do. Why? He doesn't say, precisely. Is it a negative gesture on the part of an architect who is a bit tired of design by committee and community pressure? Probably. Is it an emphatic attempt to strip away the fac,ade to expose the underlying structural reality of practically all our new buildings? Most likely. Is it intended ironically, as a sign whose very muteness prompts questioning responses? I suppose so.

But the trick is, it works. One won't forget the space it defines, partly because the wall itself is memorable without being overpowering, and partly because the space is, all on its own, quite an attraction. Schwarz was not so fanatically proud of his creation that he failed to provide for the softening effects of green (though at this point, with only a few scraggly trees installed, one has to take his word for it). And though one can, as I said, walk right through the space, there also is the opportunity to step down into a second courtyard -- in plan, a triangle within a triangle, and in three dimensions a place within a space, a high-walled retreat in the middle of a city block.

There's no guarantee that this as yet unleased place will be used by a restaurant, but that was the idea. With some luck, this will happen, and we must hope that it does. When the courtyard comes alive, this admirable and unusual building will be getting the happy ending it deserves.