In the 1950s, it was the in thing for the hip and the bright. By the '80s, it was definitely out. Now, in the '00s, it's practically historic, back in demand -- and in danger of passing away.

Modern architecture, that is. Once upon a time, the Triangle was a hotbed for the style, which eschewed the old standards and emphasized utility, structure and wide-open spaces.

Two examples from modernism's heyday and one brand-new revival open themselves today (Saturday) in a "Modernist Architecture Mini-Tour."

"You don't really get it until you walk in one of these houses, but they are different," said George Smart, a Durham executive consultant who created the Triangle Modernist Houses Web site (www.trianglemodernisthouses.com) in October as "An Educational Resource and Archive for Modernist Residential Design."

"I've discovered a following," he said.

The tour opens at 2 p.m., with a shuttle running from the parking lot at St. Stephen's Episcopal Church to three homes in southern Hope Valley: one built in 1958, one built in 1963 and the other "brand-spanking new," Smart said.

At each stop, the architect will be on hand -- Robert W. ("Judge") Carr and Bill Waddell of Durham and Brian Shawcroft of Raleigh. Saturday's Durham tour is the first in a series Smart plans to carry on to Chapel Hill and Raleigh.

"There's such a groundswell of interest in modernist," said Grant Samuelson, an architectural-history buff and tour volunteer. "It was a period of time we thought technology and clean living would save us all. ... An optimistic spirit of American design that we could do something different."

Actually, the Modernist or International style began in the 1920s in Europe as a rejection of classical forms and decoration and an embrace of modern building material and technique with the attitude "form follows function."

Frank Lloyd Wright was the best-known U.S. practitioner, but modernism dominated American architecture for several decades in the mid-20th century. N.C. State University's School of Design promoted the style, bringing in Wright, Mies van der Rohe, Walter Gropius and other modernist luminaries to inspire its students. NCSU graduates went on to design hundreds of modernist buildings and houses all over the Triangle.

"This tour is speaking to that repertory," said Derek Mangum, a real-estate salesman who sees a growing market for mid-century residences. (The two older houses on tour are for sale.)

"I love the Modern homes," Mangum said. "When I'm walking through these homes I feel at home. I can feel the architecture."

Generally speaking, modernist houses are characterized by glass, concrete, right angles, horizontal lines and harmony with the landscape. They are informal, open and relaxing, Smart said.

"Unfortunately, they weren't very popular."

Homebuyers favor the past, he said -- as attested by the neo-traditional subdivisions of the past 35 years. Still, some Modernist features, such as open-space kitchens, are now in vogue, and Modernism's use of space is "extremely efficient," he said.

At the same time, Modernism is getting old enough to be appreciated by historic preservationists.

"This era, which represents the mid-20th century and its break from the classical genre, is coming into its own," said Cathleen Turner, regional director for the nonprofit Preservation North Carolina.

"They are an important architectural representation of a point in time of our history. ... In some cases, they are works of art, no doubt."

Modernist houses are increasingly passing their 50th birthdays, making them eligible for official "historic" status. But, because the style is just now getting preservationist attention, Modernist properties are being torn down for redevelopment.

"We might not be there yet about what's important," Turner said. The tour is "a chance for people to go and see and experience these buildings and decide for themselves ... what's special."