And we actually have another architect to thank for its existence. In 1930, Philip Johnson—a relatively unknown American architect at the time—asked Mies to design his apartment in New York City. The German design star had just produced the famed Barcelona Pavilion and been named the director of the Bauhaus, but he decided to take the interior design job. The thinking is that Mies saw it as an opportunity to debut some of his newly minted furniture designs in the U.S.

One such design was a tufted daybed that shared the same lines and proportions as the signature chairs Mies had designed for the Barcelona Pavilion. Like a sleek, low-slung bench—accented with a cylindrical bolster pillow—it was as handsome as it was useful in a small, city apartment.

Paul Galloway, collection specialist at MoMA (where the Barcelona couch is part of the permanent collection), appreciates how the daybed is “an extremely simple way of delineating space.” It can separate a large room, sub-in for a standard sofa or simply sit against a wall or under a window.

The low profile is also what makes it so alluring, he says. That's why Johnson wanted another one—this time at his country retreat nestled into the woods near New Canaan, Connecticut. The suite of Barcelona furniture, including the low daybed, allowed for clear views through the walls of glass. It's here that the daybed rose to cult status. And that original piece remains among the house's minimal decor to this day.

The luxuriousness of the design actually comes from the precision with which it's engineered and constructed. The materials are solid and unimpeachable—and still built according to the original workshop specifications. Then as well as now, the allure of Mies's furniture is at once functional and fashionable.

While it is a mass-produced item, each piece consists of 72 individual panels that are cut, hand-welted and hand-tufted with leather and buttons produced from a single Spinneybeck cowhide. Upholstery straps are stretched over a rubber webbing for cushion support while the bolster is secured to the cushion platform with additional straps and lock snaps. It sits atop a platform frame cut from African Sapele Mahogany, finished with a protective clear lacquer, and supported by polished tubular stainless steel legs.

Not surprisingly, these materials and meticulous build process makes the daybeds somewhat difficult to produce. The Wells Furniture Company originally manufactured them in small batches for the first few decades, but Knoll took over production in 1964 and continues crafting the daybeds today. In fact, Knoll—not Mies—is credited with naming the daybed “Barcelona” in 1987, after the piece's clear resemblance to the Barcelona chair and stool designed for that famed pavilion that put Mies on the map for so many of us.