Los Angeles, despite its sprawl and smog and traffic, may well be the nation's most exciting architectural laboratory.

Any visitor to Los Angeles looking for both new and old architectural experiments will not be disappointed. From the banal to the ugly, from high to low tech, from shingle style to art deco, from Bauhaus to bungalow, Los Angeles has it all -- for those with a good map and a taste for adventurous driving.

One of the primary objectives of my recent trip to Los Angeles with University of Maryland architecture students was to see some of the city's most well-known and occasionally off-the-wall architecture. Familiar to us from publication in architectural periodicals or history books, these buildings really have to be touched to be truly believed, understood and appreciated.

Of course, no survey of Los Angeles architecture is meaningful without taking into account the special character of the city.

Southern California is a desert environment brought to life by fresh water and spirited people. The mild, accommodating weather, perfect for shooting films year-round, puts little pressure either on inhabitants or building materials. A seemingly inexhaustible supply of land to the north, south and east, coupled with freeway building, allowed the city to grow with few constraints.

Although the genealogy of Los Angeles can be traced to the 18th century and California's mission settlements, it is fundamentally a 20th century city whose growth was spurred on by waves of westward migrants, unfettered economic opportunities, agreeable climactic conditions and the automobile.

It's been said that California is not a state but a state of mind, and that certainly seems evident in Los Angeles. A kaleidoscopic realm of people, neighborhoods, topography, vegetation, streets, buildings, graphics and food, Los Angeles is the epitome of an "anything goes," collage culture. It also is the place where fantasy and reality commingle and become confused.

Architecturally, this has produced what could fairly be called collective visual cacophony, a hodgepodge of free-style, ad hoc, "let's pretend" design gestures that rarely add up to more than the sum of their parts. Los Angeles' primary imagery remains the neon-lit commercial strip -- as if Georgia and Wisconsin avenues, Rockville Pike and Rte. 1 were extended over many hundreds of square miles. It's perfect for Disneyland.

Yet Los Angeles' inclusivist, laissez-faire philosophy about itself has yielded many fascinating works of architecture. Even the chaos and incoherence routinely observed along the principal commercial streets crisscrossing the city have been embraced positively as a theory of design. Individual buildings and building interiors, their components intentionally fragmented, fractured, collided and lit with neon, clearly draw inspiration from such strips.

California's most celebrated modern architect of the moment, Frank Gehry, has cultivated a species of architecture that could have been spawned only in Los Angeles.

Gehry's projects, of which we saw several, appear at first to be primarily works of art, not buildings -- abstract sculpture rather than architecture. Like some of his modernist predecessors, Gehry obviously delights in juxtaposing varieties of basic geometrical or constructional forms -- planes, cubes, pyramids, cones, cylinders, vaults, columns, beams -- to make his spatial and volumetric compositions.

But unlike most architects, he employs highly conventional materials -- chain-link fencing, plywood, wire glass, asphalt shingles, sheet metal, plastic -- in extremely unconventional ways. He purposefully offers up bizarre and eyeball-jarring visual orchestrations that can't be ignored, that loudly shout "check this out!" with their assertive incongruities.

Inside his buildings, he freely navigates between two poles -- low-cost, pragmatic minimalism (drywall, plywood, vinyl base) and tony, highly decorated, radical stage-set.

We ate Mexican food at a Gehry-designed Venice Beach restaurant whose interior exploited swamp and maritime motifs -- slightly abstract stuffed alligators, fish bouquets and an octopus hung from the ceiling -- along with luminous slabs of alabaster (was it real or plastic?). Nearby, Gehry designed a beach cottage whose most memorable feature is an elevated box accessible by ladder from the patio on the ocean side; it's a ministudy in the form of a lifeguard's watchtower.

However, Gehry's funky artistry is still that of an architect who makes real buildings and usable spaces, as he did when he designed the recently built Hollywood public library or, earlier, the Loyola Law School and the interior of Los Angeles' contemporary art museum.

While each of these is unmistakably a Frank Gehry visual production, initially grabbing your attention with its offbeat moves, they all seem to work as architecture, providing commodity and firmness as well as delight.

Other Los Angeles architects, mostly younger than Gehry -- who began practicing in the late 1950s as an orthodox modernist -- are likewise aggressively stretching the frontiers of design, typically with such projects as houses, restaurants, shops and even churches. Gehry, Charles Moore, Robert Venturi and a handful of European and Japanese architects are their mentors.

Los Angeles' propensity for experimentation is a longstanding tradition fostered by avant-garde mentors for previous generations of architects. Frank Lloyd Wright, Rudolph Schindler, Richard Neutra and Irving Gill built some of their earliest works in Los Angeles, houses that at the time represented radical departures from conventional styles.

Here were introduced some of the modern movement's favorite and most familiar elements: flat- and low-pitched overhanging roofs, cantilevers, glass walls, thin mullions, horizontality, modular concrete blocks, exposed steel structural frames and the "open plan" -- flowing space instead of enclosed rooms.

Yet Los Angeles still contains thousands of traditional buildings. The dominant types derive from Mexican and Spanish Renaissance architecture transformed into Spanish colonial and mission styles.

Los Angeles fortunately has preserved many of its mature residential neighborhoods full of white and pastel-colored stucco houses and apartment buildings, some with lushly planted courtyards. Traditional "casas" range from modest bungalows in Hollywood to huge villas in Beverly Hills and Bel Air.

We continually made comparisons with exotic, semitropical places that some of us had visited -- Spain, North Africa, Greece and Florida. We also speculated that what worked in Los Angeles would never work in Washington, not just because of ecological or historical differences, but because Los Angeles is a different culture. Los Angeles seems more tolerant and venturesome, more willing to suspend disbelief architecturally. We wondered if architects and clients in cities like Washington, so strongly attached to classical motifs imported from England, France, and Italy, ever could -- or should -- be as esthetically far-reaching as those in Los Angeles. If so, we might have more fun.

Roger K. Lewis is a practicing architect and a professor of architecture at the University of Maryland.