An unlikely downtown Dallas high-rise is on its way toward becoming an official historic landmark: One Main Place, which is but 48 years old.

At the request of the building's New Orleans-based owners, the city's Landmark Commission voted unanimously Monday afternoon to begin designation proceedings. Should the 33-story tower on Main Street, across from Belo Garden, receive the Plan Commission and City Council's blessings, it will become one of downtown's youngest landmarks alongside such elders as the 105-year-old ​Adolphus Hotel and the circa-1943 Mercantile Bank Building.

The owners, who recently converted some of the high-rise into a Westin hotel, want the landmark designation for one reason: the historic tax credits that come with it. And the concrete-grid and exposed granite exterior — which would be protected from alteration under the city's strict preservation rules — is unlikely to change. The building is fairly "set in stone," in the words of Jay Firsching, a senior historic preservation specialist at Architexas.

Besides, the building — designed in 1964 by Skidmore, Owings and Merrill — is already a landmark.

Two years ago, Firsching got it added to the National Register of Historic Places, in large part because of what it was supposed to be — "the first of a three-phase superblock project proposed for downtown Dallas in the 1960s," according to documents submitted to the U.S. Department of the Interior. "The development was intended to serve as a catalyst project for the revitalization of downtown."

On Monday, Firsching told the commission the story of One Main Place, which, he said, was born from the idea that in the 1960s, "downtown was slowly dying because of the pressures of development and density." The city center, he said, was simply "becoming an unpleasant place."

At the same time, planners were reheating Le Corbusier's concept of the self-contained "superblock" upon which the so-called Cities of Tomorrow would be built. The notion was that people would live, work and play in a single mammoth building that dug deep beneath the ground and reached high into the sky. One Main Place was to be the beginning of a project that would have erased downtown — "from the [Dallas County] Records Complex to the Wilson Building," Firsching said — and remade the city in its towering image.

The Westin Downtown is at One Main Place in downtown Dallas. (David Woo/Staff Photographer)

The concept, he said, was "ambitious," to say the least. But even its failure, he told the Landmark Commission Monday, "tells the story of Dallas planning from the 1950s to the '80s."

And, as Firsching reminded Landmark Commission members Monday, One Main Place is tied, for better or worse, to the downtown tunnels proposed by Montreal urban planner Vincent Ponte. Said Firsching on Monday, One Main Place is "the center and genesis of the tunnel system."

Architect Daron Tapscott, who heads up the commission's designation committee, acknowledged that most historic landmarks are at least 50 years old. But, he said, One Main Place easily fit the definition: The building, he said, ties into "the larger timeline of city planning and architecture," that which is and that which was never meant to be.