OAK PARK; STALKING THE ARCHITECTURE OF FRANK LLOYD WRIGHT; Chicago suburb is also home of Hemingway, Burroughs

Every Sunday afternoon, crowds gather in the leafy village of Oak Park to engage in a form of house-hunting seldom seen in American suburbs. Alone, in pairs, and in larger knots shepherded by guides,they stand their ground and gaze fondly at the blocky stucco houses. They have come not to buy but to admire, and the object of their affection is Frank Lloyd Wright, who during a flurry of building at the turn of the century left Oak Park with two dozen houses and a memorable church designed in his revolutionary prairie style.

Wright may have cast the biggest cultural shadow on Oak Park, but not the only one. Ernest Hemingway was born and raised here, Edgar Rice Burroughs of Tarzan fame wrote 11 novels in a house on Augusta Street, and a number of other important figures in journalism, literature, scholarship, and related fields made the village a sort of middle-class, middle-American Athens.

Eager to pick up both the Wright and Hemingway trails, a friend and I hopped the El in the Chicago Loop one flowering Sunday morning and made the easy 20 -minute ride west of the city. There was time to eat before the 2 p.m. architecture tour. Deciding not to fight the lines in front of the obviously desirable Cheese Cellar, we settled into an honest cafe named Jamie's beside the El tracks on South Boulevard and Oak Park Avenue.

On pleasant Sundays as many as 150 people gather for the Wright tour, which begins at the Unity Temple, a Universalist-Unitarian church badly in need of the restoration project planned for it. This bold, nearly windowless concrete church was Wright's first public building, and the prosperous, conservative Oak Parkers were not ready for it. ''No front door? No religious symbols? These Victorians asked how can it be a church?'' said the guide, Lyman Shepard, as we listened from the chapel pews.

Shepard, a dyed-in-the-wool Frank Lloyd Wright fan, is a stockbroker who works endlessly as a volunteer for the Chicago Architecture Foundation. His steel glasses and wavy gray hair somehow place him in an earlier era; when he effects the famous sweeping cape and pork-pie hat as he does for occasional dramatic depictions of his hero, he looks absolutely Wright-like.

Of course, Wright fandom has only come back in style recently. For three decades the strongest force in American architecture was out of favor, thought too rustic and nativist. Now his houses, even his sketches, are treasures, and Oak Park is a shrine.

Finished with his praises of Wright, Shepard sent us into the bright afternoon in three small groups, each led by a volunteer guide. As we started up the oak-lined blocks, our leader, a lawyer named Jim Karela, said: ''Don't stare in the windows of these houses too hard and try to stay off the lawns, of which the owners are proud.''

Our first stop, on Kenilworth, was to see an example of the very architecture Wright was rebelling against when he worked and lived in Oak Park from l889 to l 909: a massive, fanciful Victorian pile with witch-hatted dormers. ''These people had money and sophisticated taste, remember,'' said Karela, ''so it was a fertile ground for Wright's work.''

On a curving side street, we came upon a flat, geometric house from 1909 - a cubist painting among Romantic landscapes. Where was the entrance, several of us asked. ''As always, it was well hidden,'' said Karela. ''Wright believed in protecting the privacy of his customers. That's why his porches have high ledges.''

Some of the Wright projects in Oak Park were remodelings of older buildings. One such, at 313 Forest, showed the Japanese influence on the architect with its pagoda-style roof. On the lawn beside the house I spotted a notably un-Wright-like piece: a charming gazebo that had been a ticket booth at the 1893 Columbian Exposition in Chicago. At the Nathan Moore residence next door, one couldn't help asking about the uncharacteristically fussy peaked roof and dark-timbered construction. ''This was 1895, early in his career,'' Karela answered, ''and also at the time of the great depression (of 1895) when he took commissions he might not have taken in later years.''

We finished at the one-time home and studio of Frank Lloyd Wright, a dark-framed, lead-windowed building that is being restored to its 1909 flavor with hard-won funds. In the adjoining Gingko Tree book shop there are pincushions and place mats in Wright's geometric design, T-shirts and aprons bearing his likeness, plus sets of tiny German building blocks like the ones his mother gave him in his infancy. The blocks sell for a whopping $33.

Now we were off along the Hemingway trail. We stopped at a modest white witch-hatted house at 339 Oak Park Avenue, where Hemingway was born on July 29, l899. He will be honored this summer with a dual celebration of the 85th anniversary of his birth and the 30th year since he won the Nobel Prize for Literature. A local group, choosing not to believe that Hemingway described Oak Park as ''a village of broad lawns and narrow minds,'' will hold a series of dinners, discussions, lectures, and tours July 20 and 21. (For more information write the Hemingway Celebration, 559 Ashland, River Forest, Ill. 60305.)

Hemingway left Oak Park in 1917 for a job on the Kansas City Star, followed by wartime service as a Red Cross ambulance driver in Italy. That brief but telling chapter in his life is footnoted in Scoville Park, a few blocks from where he grew up. There, among hundreds of names etched into a greening bronze tablet at the base of a World War I monument, I found: HEMINGWAY, EM. Then, as he might have written, we gathered up our thoughts and walked back to the El in the sun.