The entire district is gated, private property, closed to the casual visitor.

The significance of Blackstone Court Historic District is more historical than architectural, though enough physical evidence of past history remains to create a sense of the former place and time in this unusual mid-block enclave of five structures on a blind alley.

The north line of the ally [sic], Blackstone Court, follows the north line of an early trail shown on U.S. Coast Survey maps of the 1850's and 1860's, a trail that ran from town toward the Presidio, around the north end of Washerwoman's Lagoon (now drained and filled; so named for the Gold Rush laundries). The western end of Blackstone Court is the western edge of William Eddy's 1849 Lagoon Survey which set up a grid parallel to Market Street, facing the view through the Golden Gate.

On a lot alignment perpendicular to the north edge of the old trail, 9-11 Blackstone Court appears to date from the 1850's because of its Gothic Revival veranda and its interior plan and finish. It is first documented on its site in 1893 (possibly moved to clear a street right-of-way designated by the Laguna Survey of 1889-91). Before 1899 it was raised a story by the Favilla family from North Beach, very early Italian-American residents in what became the Marina District.

Abraham House, 30 Blackstone Court, was constructed in 1885 by Charles Abraham, and enlarged by him in 1905. Abraham was the horticulturally significant founder of Western Nursery, which operated on most of this block from 1885 to 1947. It was the last expression of the Cow Hollow/Marina District agricultural enterprises.

An Australian peppermint tree and a Monterey Cypress appear to date from the nursery. All of these elements combine to present a unique physical expression of the pre-1906 settlement patterns of this section of the City: the pre-Gold Rush trail, the lot lines perpendicular to it, the nursery, the modest old houses and early, pre-1900 Italian-American investment in the Marina District.