Robert Carroll Davenport, 96, a former administrative officer in the Agriculture Department whose interest in real estate led him to build two large subdivisions in Northern Virginia's Mount Vernon area, died of pneumonia and congestive heart failure Feb. 6 at his farm in Fauquier County.

Mr. Davenport's most notable development was the contemporary-design houses of Hollin Hills. The first house was built there in 1949, with building continuing on the 225 acres of forested, hilly terrain in southeastern Fairfax County until 1971. Mr. Davenport and his family lived in the development's model homes and a house trailer before he bought a 1,000-acre farm in the Markham area of Fauquier County in the mid-1950s to breed Black Angus cattle.

When he retired in the 1970s, he moved to a farm near Delaplane and served as chairman of the Fauquier County Planning Commission. In the 1980s, he was selected as Fauquier's Man of the Year and was given the Virginia Cattleman of the Year award in 1992.

In all, Mr. Davenport built 458 houses -- based mainly on the innovative designs of noted Washington architect Charles Goodman -- in Hollin Hills.

A crew of 30 to 40 workers, under Mr. Davenport's direction, carried out those plans, some of which called for brick split-level ranch houses with low, sloped gable roofs and panels of floor-to-ceiling windows for an abundance of natural light.

Landscape architects were consulted to maximize tree preservation and configure the houses to fit the contours of the land, which Mr. Davenport had bought in a courthouse auction. Mr. Davenport donated land for a school and set aside parkland throughout the development. The approach was unusual, given the boom at the time for look-alike tract houses and the pressures from the post-World War II housing shortage.

By 1951, when 70 houses were built or under construction, Hollin Hills was selected by the Southwest Research Institute as the nation's outstanding development. The area and specific streets within Hollin Hills received other awards through the years, including the 1982 Test of Time Award from the Virginia Society of the American Institute of Architects.

While Hollin Hills, with its 11 cul-de-sacs and looping streets, drew national attention for its housing and land planning, its uniqueness fostered a community spirit among its residents, said Mr. Davenport's son, Tom Davenport, of Delaplane.

Mr. Davenport was born in Norfolk, Neb. In 1929, he graduated from the University of Nebraska, where he was a track star and a member of the record-setting half-mile relay team. After moving to Washington in the mid-1930s, he was working for the Agriculture Department and living at the Buckingham garden apartments in Arlington when he, his wife and a group of tenants formed a co-op that built 20 rambler-type cinder-block homes about two miles from Hollin Hills.

The development, named Tauxemont and one of the first of its kind in the Northern Virginia suburbs, grew in later years. Mr. Davenport quit his government job in the 1950s to work full time building houses and developing communities.

His wife, Elizabeth Barbara Davenport, died in 1999.

In addition to his son, he is survived by a daughter, Rebecca Davenport of Beaufort, S.C., and two grandsons.