The D. Blakeley Hoar Sanctuary is located in southwestern Brookline, behind the Baker Elementary School. It borders on Gerry Road to the southeast, and Boston to the east and north. It is connected to conservation lands in Boston and Newton. This natural, undeveloped 25-acre area contains several typical plant communities. A trail with several boardwalks circles the sanctuary. The south branch of the Sawmill Brook flows through the sanctuary from east to west. It cuts through an extensive red-maple swamp and vernal pool habitat. Cliffs and outcrops of "puddingstone" (Roxbury conglomerate) define the north edge of the sanctuary.

A wooded upland is found in the northeastern part of the sanctuary. The most common trees here are maple, oak, cherry, and birch. There is an understory of shrubs and an herbaceous layer of woodland plants. Adjacent to Gerry Road is a grove of trees, once part of a beech-hemlock forest. Many of the hemlocks have been damaged by woolly adelgids; wind damage has taken a toll on the larger trees. There has been extensive damage to the understory, shrub layer, and herbaceous plant layer, partly due to over-use.

The sanctuary is used for wetland protection, conservation of wildlife habitat, environmental education, and passive exploration such as bird watching and nature walks. Active recreation such as ball games, bicycling, and dog walking are not permitted in the sanctuary.

The Town acquired the sanctuary in 1961 with a bequest from D. Blakeley Hoar, a noted Brookline lawyer and conservationist, who stipulated in his will that a portion of his estate be used to establish a bird sanctuary in Brookline. The Conservation Commission assumed responsibility for the sanctuary in 1969.