When interiors partner Stephen Apking got an internship at Skidmore, Owings &Merrill in 1979, he went to work every day at a building across the street from Lever House, the New York landmark by the firm's legendary partner Gordon Bunshaft. Even back then, Apking says, he was acutely aware of Lever House's importance in the history of the International Style—and of SOM: "Lever House was part of our outward identity and our inner sense of self." More than 20 years later, he had a rare chance to work on that storied property when its new owners, Aby Rosen and Michael Fuchs of RFR Holding, brought SOM back to undertake a restoration from the outside in.

The comprehensive job involved several divisions at SOM. While partners David Childs and Carl Galioto restored the glass curtain wall, Apking worked on offices for RFR and aluminum producer Alcoa. "As much as we knew about the building, it was still surprising for me, as a designer, to walk those floors for the first time," Apking says. "We all see Lever House as a 'glass building,' but the windows don't go from floor to ceiling. When you walk in, you're hit with the fact that the view is not panoramic. It's sort of a ribbon." In 1950, when Lever House was designed, fire codes required a 30-inch-high brick bulkhead on every floor. (Diagonally across Park Avenue, the Seagram Building features floor-to-ceiling windows, thanks to a change in the law by 1958.) Yet Bunshaft ingeniously designed Lever House's spandrels to make the curtain wall's exterior seem as if it's all glass—an approach emulated by architects for decades to follow.

Working on Alcoa, Apking discovered that each 8,700-square-foot floor plate was designed to conform to a grid with a basic unit of 4 feet 9 inches, slightly but significantly smaller than the 5-foot modules commonly used now. Besides creating more intimate proportions, this difference made spaces more efficient. "The module was one that SOM and others had used consistently in the '50's and '60's," Apking relates. "It's one of the reasons that Lever House looks so beautiful—taller and leaner." (Especially since the 24-story slab is famously turned at a 90-degree angle to the street.) "Experiencing that module has actually changed the buildings we're designing today," he adds.

When the time came to select finishes and furnishings for both RFR and Alcoa, the makeover took cues from Lever House's exterior, echoing its elegant polished glass and shiny stainless steel. RFR's office zone, for example, is partitioned by clear glass framed with stainless steel. Floating walls of aniline-dyed maple give a nod to Raymond Loewy's original Lever Brothers interiors, which featured wooden enclosures for clerical areas. "It's a holistic landscape," Apking says. "The interiors are an extension of the building itself."

Opposite: When Lever House opened in 1952, it was the first glass curtain-wall tower in New York. Photography: Ezra Stoller/Esto.

Top: The 24-story tower is turned 90 degrees from Park Avenue, atop a raised two-story base and an open plaza. Photography: Ezra Stoller/Esto. Bottom: The lobby restoration was completed in 2003. Photography: Florian Holzherr.

Top: At RFR Holding, which owns the building, the COO and principal's offices open to the third-floor terrace. Photography: Jimmy Cohrssen. Center: Raymond Loewy conceived a novel open plan for the corporate operations of the Lever Brothers soap company. Photography: Ezra Stoller/Esto. Bottom: A corridor at RFR serves as a gallery for large-scale artworks such as a silk screen by Andy Warhol and Jean-Michel Basquiat. Photography: Jimmy Cohrssen.

Opposite: The podium's underside displays Sarah Morris's Robert Towne installation through December 3. Photography: Mark La Rosa.

Top: A photo of Loewy's office for Lever Brothers became a touchstone for Alcoa's current open plan. Photography: Ezra Stoller/Esto. Bottom left: In today's reception area at the aluminum giant, the desk's polished granite counter reflects an acrylic on canvas by Cleve Gray. Antonio Citterio designed the chairs. Photography: Jon Miller/Hedrich Blessing. Bottom right: Glass encloses the company's conference rooms as well as a staircase that connects seven floors. Photography: Jon Miller/Hedrich Blessing.

PROJECT TEAM (ARCHITECTURE): T.J. GOTTESDIENER; JOHN OSTLUND; LOIS MAZZITELLI; JONATHAN STEIN. PROJECT TEAM (RFR HOLDING): WOODSON RAINEY; MARY BROADDUS; JAMES CIFUENTES; JANE COHEN; HAROLD GROSS; YA-CHING HSUEH; CORRINNE KARMIEL; CYNTHIA MIRBACH. PROJECT TEAM (ALCOA): T.J. GOTTESDIENER; JUDY BETTS; JANE COHEN; HAROLD GROSS. FLOORING (RFR HOLDING HALL): SHERWIN-WILLIAMS COMPANY. BASE MATERIAL: DUPONT. RECESSED CEILING FIXTURES: NULUX. CHAIRS (ALCOA RECEPTION): BB ITALIA. CUSTOM RUG: VSOSKE. CUSTOM COUNTER: CUSTOM INTERIOR DCOR. ENCLOSURE INSTALLATION (ALCOA STAIR HALL): COORDINATED METALS; GALAXY GLASS STONE (GLASS). CEILING SYSTEM: ARMSTRONG. CARPET: EDWARD FIELDS. MILLWORK (ALCOA): WILLIAM SOMERVILLE. ART CONSULTANT: ART ADVISORY SERVICES.