OWATONNA, Minn. - A small-town banker with refined tastes. A brilliant if difficult architect on the downside of his career. A town that over the years came to recognize and preserve the gem in its midst.

The result of this confluence of factors is what some consider - 94 years after it was built - the most beautiful bank in the world. Designed by the renowned Louis H. Sullivan, more famous for his role in developing the urban skyscraper, the former National Farmers Bank is world-class architecture in an unlikely small-town setting.

In this town of 22,000, in the midst of a southern Minnesota landscape of farms and factories, the bank - now part of the Wells Fargo chain - emerges as a small but imposing structure, a 68-foot cube of brick with large, arched stained glass windows on two sides.

As elegant as the bank's exterior is, though, it barely hints at what lies inside: a soaring, cathedral-like space awash in natural light and color, its walls painted with murals and trimmed in elaborate stencilwork and terra cotta tiles.

"I want a color symphony," Sullivan had written banker Carl Bennett during the building's construction. "I want something with many shades of the strings, and the wood winds and the brass."

Sullivan was certainly speaking Bennett's language: Educated at Harvard, Bennett acceded to his father's wishes that he abandon his dreams of becoming a classical musician and return home to the family banking business. That the two found one another - the frustrated artist turned banker and the visionary architect - is part of the allure of the building they created.

"It's not only an intriguing building," says Larry Millett, a former newspaperman and author of the definitive book on the building, "but an intriguing story."

Millett's book, The Curve of the Arch, traces the story of these two men, plus a third, George Elmslie, an architect who worked as Sullivan's draftsman and designed much of the elaborate ornamentation that gives Sullivan's buildings their signature look.

Born in Boston, Sullivan eventually made his way to Chicago, where he worked for William LeBaron Jenney, considered the father of the skyscraper for building the first tall structure supported by an internal skeleton of iron and steel. Previously, buildings were limited in height because the walls bore the entire weight of the structure, meaning they had to become thicker and thicker as additional floors were added.

But if Jenney's technical expertise led to the first skyscraper, a 10-story building constructed in Chicago in 1885, it was not until Sullivan began to design tall buildings that the new form realized its true potential. Sullivan's genius was to fully express the skyscraper's soaring height; by recessing the horizontal elements and highlighting the vertical ones, he drew the eye upward so that, indeed, the building visually scraped the sky.

As influential as Sullivan would prove to be in the history of architecture - among his proteges was Frank Lloyd Wright, who considered him his "lieber meister" - by the turn of the century, he was on a downward spiral. Arrogant and uncompromising, Sullivan increasingly was alienating colleagues and clients - he and his partner on the great skyscrapers, Dankmar Adler, split up, and he fired Wright for working on the side on his own buildings. His personal life was in no better shape, and he was drinking heavily.

"At this time, he was basically a nonpracticing architect and living in obscurity," says Millett, formerly the architecture critic of the Pioneer Press in St. Paul, Minn.

And yet the banker Bennett, who traveled occasionally to Chicago and was well-read, knew of Sullivan's work and his writings, recognized a kindred spirit and hired him in 1906 when he needed a new bank building.

While a small bank in an out-of-the-way Midwestern town may seem like a comedown for an architect of Sullivan's stature, neither he nor Bennett treated it as such. Sullivan's grand design for the building, which was completed in 1908, ended up costing Bennett about $125,000, a huge sum for that time and certainly that place.

"I looked into that, and at the time, banks of that size cost about $5,000 to $10,000, so the Bennetts spent more than 12 times that," says David Bowers, a Minnesota architect who has worked on several restorations of the Owatonna bank. "It was a very prosperous town, and Carl Bennett saw the bank as reflecting that prosperity."

For all its high style, though, the bank hewed to Sullivan's famous rule, "form ever follows function." There was an exchange room, where bankers could bring in wheat, milk or other products to trade, and a "women's room," for the ladies at a time when business was still an all-male province.

The bank is surprisingly well-preserved, given what it has been through: In 1926, the farm economy collapsed and with it the Bennett family's bank. It has been sold several times, and endured terrible "improvements" such as the installation of fluorescent lights and the dropping of a false ceiling covering the skylight. But it survived long enough to become a national landmark, and subsequent renovations have restored much of Sullivan and Elmslie's original ornamentation and intent.

For those who work and bank there, it remains a delight - the elaborate "electroliers" (electronic chandeliers) that hang in the lobby, the ever changing colors as the sun or clouds drift over the skylight, the visitors who come from around the world to see it.

"One time, there was a British film company here," said Ken Wilcox, president of the bank until he retired four years ago, "and they'd lay on their backs to film the ceiling and you'd have to step over their bodies."

The bank proved to be the beginning of the final chapter of Sullivan's career - it led to commissions for seven other small-town banks across the Midwest, a string of charming jewel boxes, small in scale but grand in design. But the work eventually dried up and he died, impoverished in 1924.

Today, however, his legacy is intact, and something Bennett once said about the Owatonna bank proved prophetic.

"The owners of the building feel that they have a true and lasting work of art," Bennett said, "a structure which, though built for business, will be as fresh and inspiring in its beauty one hundred years from now as it is today."