A rock, a string and gravity. Those were the basic elements that John Dreyfuss chose to work with when he set about creating "Alexander's Lure," his monumental, plumb-bob-shaped sculpture inspired by the life of Alexander the Great.

"Nothing could be simpler than a rock hanging from a string, which is what a plumb bob is in essence," says Dreyfuss. "But controlling that hanging shape, working with gravity, those were major challenges for me with this piece. Even as the exhibition was approaching, I wasn't sure it was ready to be turned into metal."

That uncertainty had Dreyfuss leaning toward showing a maquette, a wax-surface, preliminary model of the sculpture, at his solo show currently at Hemphill Fine Arts. But at gallery owner George Hemphill's urging, he put aside his doubts and had "Alexander's Lure" cast in iron.

It was the right decision. Rarely has a single work so completely captured Dreyfuss's devotion to classical form, fascination with surface texture and obsession with architecture and art history.

The giant plumb bob, weighing 1,200 pounds, hangs in the center of the gallery's front room, suspended from the ceiling by a steel cable. The surface of the elegant, spare form has been oxidizing since it came out of the mold, creating an organic patina that seems to change color and texture before the viewer's eyes. Is it rusty orange, gray or black? Does it resemble sandstone, velvet or pig iron? The answer is all of the preceding and then some. At times, the metal mass also seems to move slightly, as if the sculpture were realigning itself to unseen changes beneath the Earth's crust.

Letting those physical and chemical phenomena go their own ways is something of a departure for Dreyfuss, whose previous works have, on occasion, seemed too tightly controlled. Dreyfuss is a highly cerebral person with a degree in architecture and an abiding interest in the internal architecture of his sculptures. That passion has prompted him to install a sophisticated computer-imaging system in his large, sunny studio in Georgetown. Using computer modeling, he can study his creations inside and out from every conceivable angle.

The architectural approach has helped him create some remarkable sculptures for "East West Passages," his three-part collaboration with choreographer Dana Tai Soon Burgess that is based on the story of Alexander the Great. "Gandhara," the second installment of that series, premiered recently at the Kennedy Center and will be touring other venues.

For "Gandhara," Dreyfuss worked with several high-tech defense contractors to create a huge sculpture from lightweight composite materials normally used in building jet fighters and spacecraft. The idea was to make a monumental form that was light enough for the dancers to manipulate onstage. Three smaller versions of that piece, which bears the same title as the dance, are on display in the gallery's back room, along with schematic drawings.

While the attention Dreyfuss pays to how a sculpture is built is laudable and a vital part of his creative process, the viewer sees only the end result, not the physical or mental labor behind the object. The sculpture's effect on the viewer derives first and foremost from its form, material and surface texture.

In the case of "Alexander's Lure," Dreyfuss makes masterful use of those elements and the room in which the piece hangs to create a wealth of metaphorical possibilities. The plumb bob shape obviously evokes construction and was inspired by the 31 cities that Alexander built in his name as he led his Greek and Macedonian warriors to victory across the Middle East and Asia.

But even as new cities arose, such as what is now Alexandria, Egypt, other cities were destroyed by the great conqueror. The great iron spheroid can also be seen as a wrecking ball, waiting to swing into action. The shape also calls to mind cannonballs, fishing bobbers and, oddly enough, a church bell at rest.

While Dreyfuss is deeply involved with using cutting-edge technology as a tool in constructing his sculptures, which range from representational to abstract, he employed mostly old techniques in the creation of "Alexander's Lure." A thin line that circles the shape near the top was done by hand.

"I really did this all myself," Dreyfuss says. "I don't think I'll do another piece that way, given the technology available and the projects I'm planning, but I'm really thrilled with the way it turned out."

Dreyfuss plans to replicate the plumb bob in other materials, such as stainless steel or bronze or space-age plastic, exploring how the surfaces that can be created from those metals will affect the form's physical and psychological presence. That would be an impressive encore for his tour de force with a rock, a string and gravity.

John Dreyfuss, at Hemphill Fine Arts, 1027 33rd St. NW, through Dec. 23. Tuesday-Saturday, 11 a.m.-5 p.m. 202-342-5610.