The walls curved outward instead of in. On a wooded lot in Lincoln, Massachusetts, poured concrete rose in continuous, board-formed shapes that opened toward the surrounding trees rather than closing the family off from them, the roof slab floated on Teflon strips so it could expand and contract without cracking. That house, finished in 1965, was the work of Mary Otis Stevens, who died on July 12, 2026, in Cambridge, Massachusetts, at 98.

Stevens designed the Lincoln House with her husband and design partner, Thomas McNulty, for themselves and their three sons. The MIT Museum, which later acquired her professional archive, called her one of the most important female architects in the Northeast during the 1960s and 1970s, a judgment the house helped earn on its own. Architectural Forum commissioned a silkscreen of it for its November 1965 cover, Life magazine featured it that December, and Architecture d'Aujourd'hui and Deutsche Bauzeitung both put it in front of European readers within the year. The Architectural League of New York included her, the following year, in its traveling exhibition "40 Under 40: An Exhibition of Young Talent in Architecture." When Walter Gropius visited in the late 1960s, he told her the house was "one continuum." Buckminster Fuller, a family friend since her student days, saw in its outward-reaching curves "the negative of his positive," a counterpoint to his own inward-facing domes, according to the Harvard Design Magazine.

Stevens was direct about what the house was for. "I was against ordinary American domesticity," she said. "I didn't want my children to grow up in the conventional restrictive environment I had been brought up in." The plan removed nearly every interior door, and floor-to-ceiling glass doors linked several rooms directly to the yard; the family's more private spaces, a circular library and studio, sat at the design's center.

She had arrived at the idea by an unusual road. Born March 28, 1928, in New York City to a stockbroker father and a mother from an old New England family, Stevens grew up mostly in Old Chatham, New York, after her parents separated, then studied at the Shipley School before earning a philosophy degree from Smith College in 1949. She did not enter MIT's architecture program until 1953, compressed the four year course into three using summer terms, and graduated in 1956 with Buckminster Fuller among her mentors. She became a registered Massachusetts architect in 1964, one year before the Lincoln House was completed, according to Pioneering Women of American Architecture, the Beverly Willis Architecture Foundation's research project on women in the field.

Stevens and McNulty ran their own practice together for more than a decade, beginning in the mid-1950s, designing houses such as the Cabot House in Manchester and the Torf House in Weston for art collectors and, drawing on several years of research into New England prisons, a pre-release center on the grounds of Norfolk State Prison; the partnership also founded the publishing venture i press to put out books on urban design and planning theory. The opera director Sarah Caldwell bought the Lincoln House from the family in 1978, and it stood until developers demolished it in 2001. By then Stevens had already moved on. She taught at the Boston Architectural Center through the 1970s, cofounded the advocacy group Architects for Social Responsibility with fellow architect Sarah Harkness in 1973, and around 1975 started a new firm, Design Guild, organized around nonprofit clients, historic preservation, and what she called adaptive reuse. That practice's best-known work converted two eighteenth century barns into the Barns at Wolf Trap performing arts center in Vienna, Virginia. Design Guild closed in 1991, but not before Stevens picked up a 1984 merit award in the Jacob's Pillow masterplan competition and a 1986 wood remodeling design award from the American Wood Council and Remodeling Magazine.

Her writing traced the same commitments. She published the essay "City Is a Four-Letter Word" in 1972, and contributed "Struggle for Place: Women in Architecture, 1920-1960" to the anthology Women in American Architecture in 1977, an early attempt to put her own generation's work into a longer historical record. Two National Endowment for the Arts fellowships, in 1955-56 and 1957-58, had funded her earliest research into American settlement patterns and the history of the workplace. Looking back later on the suburban growth her generation had built against, she said plainly, "The suburbs promised no social or cultural unrest."

After Design Guild closed, Stevens returned to an earlier interest and studied music composition at the Longy School of Music in Cambridge. In 2007 she gave her professional papers, drawings, and project records to MIT, with related materials also held today in the International Archive of Women in Architecture at Virginia Tech, ensuring that researchers of her architectural generation would have her own account of the work, not only the magazines that once celebrated it.

Mary Otis Stevens spent a working life arguing, in concrete and in words, that a house or a neighborhood should open outward rather than close in on itself. The curved walls in Lincoln are gone, but the archive she built at MIT and Virginia Tech, the essay she wrote reclaiming women's place in architectural history, and the adaptive-reuse projects Design Guild left in Massachusetts and Virginia remain: material for the students, preservationists, and historians who now study the kind of freer space she spent her career trying to build.