Brookside is an enclave of eight tree-lined streets and 400 homes in Mid Wilshire, just below Hancock Park. Brookside was carved out of the original Rancho Las Cienegas (Ranch of the Marshland), owned by Mexican native Don Francisco Avila.

The neighborhood consists primarily of one-story and two-story, predominantly single-family residences in various Period Revival styles including Spanish Colonial Revival, Tudor Revival, Mediterranean Revival and French Revival; later buildings were constructed in the Minimal Traditional and Ranch styles. Brookside, a neighborhood of predominantly large, single family homes, was developed by the Rimpau Estate Co in 1920. The area, originally called Wilshire Crest, was built to attract wealthy families from West Adams.

Located in Mid-Wilshire, Brookside is located between Olympic Boulevard and Wilshire Boulevard, and includes the homes on both sides of, and between, Highland Ave and Muirfield Ave. The Park Mile commercial corridor separates Brookside from Hancock Park to the north.

The most luxurious properties were along Longwood Ave, where the developers laid out deep rear lots bisected by a natural underground stream known as El Rio del Jardin de las Flores. A natural stream, the Arroyo de los Jardines (Brook of the Gardens), runs through Brookside and onto Baldwin Hills and eventually flows into Ballona Creek. Surfacing briefly on its journey from the Hollywood Hills to Ballona Creek, the stream wanders from one side of Longwood to the other.

Not wanting the stream to run on only one side of the street, the planners developed around it, preserving some of the natural arroyos, barrancas and hills of the original tract - still there to this day. An old development plan notes that Windsor Crest is the highest elevation on Wilshire Blvd west of Western Ave, in what is recognized as the most desirable home section of Los Angeles.

Brookside prominently features several publicly owned and maintained historic resources such as the LA High Memorial Park and Memorial Branch, as well as privately owned historic sites such as the Farmers Insurance Building.

On October 28, 2015, the Los Angeles City Council unanimously passed a motion to establish an Interim Control Ordinance (ICO) for the Brookside and Sycamore Square neighborhoods to help prevent residential teardowns and the construction of oversized replacement homes as the city re-works its Baseline Mansionization Ordinance.