From the National Register nomination form of 2005, completed by M. Ruth Little:
Split-level type house with such Modernist features as a concrete block lower level containing a garage and attached carport with metal pip posts, asbestos siding, tar-and-gravel roofs, and a large interior chimney. Other features are a door with sidelights and a shallow stoop supported by an angled wooden ladderlike post, 2 wide fixed pane windows on the façade, and sliding windows on the sides. Joseph D. Rivers, an architect at George W. Carr Associates, was the owner-occupant in 1950. [1950 CD, Carr interview]
Robby Poore, whose families lived in 426 and 421 Carolina Circle, has posted some fabulous mid-century photos of Carolina Circle, and Durham in general, on his personal Flickr page. There are several albums (1948, 1949, 1950, 1950-1954, 1957, 1967, 1968, 1969, and 1970). View individual images of 403 Carolina Circle - barely visible beyond the trees - here and here.
The following information comes from the City Directories and general web searching: