The rectangle has been modified by the addition of the Marston Hills natural area in the northwest corner of the park, while the southwest corner of the rectangle is occupied by a portion of the Cortez Hill neighborhood of downtown San Diego and San Diego High School, both of which are separated from the park by Interstate 5.

The Central Mesa is home to much of the park's cultural facilities, and includes scout camps, the San Diego Zoo, the Prado, and Inspiration Point.

An early proponent of drought tolerant and California native plants in garden design, Sessions established a nursery to propagate and grow for the park and the public.

The Botanical Building, designed by Carleton Winslow,[20] was the largest wood lath structure in the world when it was built in 1915 for the Panama-California Exposition.

[24] In 1835, the Alta California authorities set aside a 1,400-acre (570 ha) tract of pueblo land in San Diego to be used for the public's recreational purposes.

[25] This land included the site of present-day Balboa Park, making it one of the oldest places in the United States dedicated to public recreational usage.

[25] Three years later, the Mexican government was forced by the Mexican–American War to cede Alta California, including San Diego, to the United States.

[26] On February 15, 1868, the city's Board of Trustees was asked to create a public park out of two 160-acre (65 ha) plots of land just northeast of the growing urban center of "New Town"—present-day Downtown San Diego.

[30] A San Diego resident learned of the plan and informed higher powers at the state level in Sacramento, California.

One of the most celebrated of these early usages was a 36-acre nursery owned and maintained by local horticulturist and botanist Kate Sessions, who is often referred to as "the mother of Balboa Park.

Her work was so progressive that she was in fact the first woman awarded the Meyer Medal for "foreign plant importation" by the American Genetic Association.

Indigenous Californians and Bajenos began to flock to the Kumeyaay village in Florida Canyon looking for work in San Diego during this period.

[2] Beginning in 1909, San Diego Chamber of Commerce president G. Aubrey Davidson suggested that the park hold an expo to coincide with the 1915 opening of the Panama Canal.

[35] Davidson believed an expo would help improve commerce (it would advertise that San Diego was the first U.S. port of call vessels encountered after passing through the canal and sailing north), build the city's population, and expand the infrastructure of the park.

[35][38][43] The Exposition's lead designer and site planner was architect Bertram Goodhue, well known for his Gothic Revival style churches in New York and Boston, who sought a regionally appropriate aesthetic to use in Southern California.

Goodhue's team, which included Kate Sessions and Lloyd Wright for landscape design, had won out over the local and more modernist Irving Gill to get the commission.

President Woodrow Wilson pushed a telegraph button in Washington, D.C., to symbolically open the ceremonies by turning on the power at the park.

Balboa Park was reconfigured by San Diego architect Richard S. Requa, who also oversaw the design and construction of many new buildings, some to be permanent.

The controversial Zoro Garden Nudist Colony, "Midget Village", and sideshow entertainments including fan dancer Sally Rand added to the lore.

[55][56] The Exposition also provided visitors with early glimpses of 'Alpha', a walking silver robot; and a strange new electrical device called a "television".

Opening ceremonies for the second season began when President Franklin D. Roosevelt pressed a gold telegraph key in the White House to turn on the exposition's lights.

[63] It remained in place until 1921, when a more permanent base was established in Dutch Flats, itself a predecessor of Marine Corps Recruit Depot San Diego.

[2][5][75] The following year two historic park structures burned down in two separate arson fires: the Aerospace Museum in the former Electric Building, and the 1935 Old Globe Theatre.

[84] To counter the increase in crime, city officials expanded police patrols in the park, and many of the individual museums hired security guards.

However, the scheduled start of construction was pushed back to February 2013 due to a legal challenge from the Save Our Heritage Organisation (SOHO).

[17] In December 2016, opponents of the traffic redirect and its associated 'bypass bridge' sued to stop it from moving forward on the grounds that it would fundamentally change the historic monument.

City Attorney Mara Elliot called this an "unjustified attempt" to delay the project, but SOHO claimed it would have adverse effects on the park and its historic integrity.

These events include free weekly concerts at the Spreckles Organ Pavilion each Sunday at 2:00 p.m., guest speakers, and annual parades, cultural festivals, and fairs.

The event celebrates Earth Day, and includes a parade, musical performances, children's area, international food, exhibit booths and information on various topics related to the environment.

[110][111] The two-day San Diego Pride Festival is held in the Marston Point area of Balboa Park each July; the 2011 event was attended by more than 150,000 people.