The museum complex centers on a 1915 residence that Irving Gill designed for philanthropist Ellen Browning Scripps. Over time, additions by San Diego-based Architects Mosher Drew and later, Venturi Scott Brown Architects (VSBA), added gallery space, an auditorium, and the entrance atrium.

In 1950, the Art Center determined that its galleries, which occupied the original Gill building required modification. The local architectural firm Mosher & Drew was hired to rearrange the interior of the Scripps House so as to create more suitable gallery space. The alterations transformed the first-floor living rooms into galleries and second-floor bedrooms into offices. In 1959 the same design firm was hired again to perform a second round of alterations and additions. At this time the changes made to the Scripps House drastically altered the original Gill design. According to Hugh Davies, La Jolla Museum director, the Mosher & Drew project succeeded in concealing the Scripps House with a more "modern aesthetic" of concrete block and colonnades. The arched entry, a trademark Gill feature, was removed and the original windows were bricked in." The alterations concealed all traces of Gill's original design on both the Prospect Street and ocean facades.

VSBA completed 52,000 sf of renovations and additions to the museum in 1996. The distinguished building had been subsequently swallowed up by the 1950s additions. VSBA created a new facade in order to enrich the Museum’s image and civic presence and to make it more inviting for visitors. At the same time, the Scripps House facade was restored and the vine-covered pergolas of the original Prospect Street garden were reconstructed to form a new entrance court for the Museum.

At street level inside, a central lobby surmounted by a star-shaped clerestory serves as a kind of courtyard, providing access to a bookstore, the auditorium, and galleries. It’s also used as a banquet hall for special gala events.VSBA also redesigned and expanded the existing Coast Room used for meetings, events, and educational activities. 

VSBA renovations also created a larger library and reading/conference room. The garden was enhanced with additional wheelchair-accessible paths and ramps while significant plants and vistas were preserved. In addition, Sherwood Auditorium was given a new entrance, refurbished seats and finishes, critically needed repairs, and new lighting and other systems.

VSBA approached the addition project by identifying an ongoing duality of existing contradictions. They created a unified composition by meshing the old and new together. The architects embraced the history of the original building and the surrounding urban context by employing direct historical imagery into their addition design. The historic facade is tied to the new design, resulting in a museum addition that clearly reflects the original structure.

The museum is located within a historic section of La Jolla, California and set upon a ridge overlooking the Pacific Ocean. The main facade faces Prospect Street and the rear looks to the ocean.

Under VSBA, the Museum’s new facades extend beyond the house facade and contain institutional-scaled arched windows whose form and rhythms are reminiscent of the other Irving Gill buildings, especially those of the Women’s Club building across the street. This thereby gently enhances the scale of the Museum and the urban unity of the building’s immediate context. 

The building occupied by the La Jolla Museum, the Scripps House, is significant to the regional history of La Jolla, California. This fact was crucial to Robert Venturi and Denise Scott Brown's design. As Venturi explained in his 1996 essay, "Design for the Museum of Contemporary Art, San Diego," the architects developed the contextual issues into a thematic framework for the addition project. Venturi immediately identified the museum's significance as an Irving Gill building and focused on the contextual importance of reviving the Scripps House memory.

The project involved the restoration of the historic Gill facade while providing new gallery space. Venturi explained the extent to which the architects went to uncover the original facade from the 1950's additions. He wrote, "We had to demolish parts of, renovate parts of, restore parts of, add to parts of the original complex of the Museum of Contemporary Art to make the inside a whole which accommodates the extremely complex program of a modern museum, and to make the outside a new civic building for the community."

Clearly, the architects believed that by focusing their design on the museum's history they would address the surrounding context as well. Robert Venturi's first project notes summed up the architect's attitude in three simple words: "Bring back Gill."

The museum's significant history and unique setting were crucial factors of the VSBA addition design. Irving Gill was an important designer for his period, partly because he developed a new building technique using poured concrete. According to his biographer, Gill believed in the honesty of materials and allowed the poured-in-place concrete to determine form, sometimes adding arches to relieve the severity of the bare geometry. The resulting structures were stark cubic forms, which must have been shocking amid late-nineteenth century Victorian neighbors. Gill's clean lines and pure geometry anticipated twentieth- century Modernist architecture.

Hall, Amanda Theresa, "Venturi, Scott Brown and Associates: An Analysis of the Architects' Approach to Additions for Historic Buildings" (2000). Theses (Historic Preservation). 300.
http://repository.upenn.edu/hp_theses/300

Photos credit: VSBA Architects & Planners 

https://www.vsba.com/projects/museum-of-contemporary-art-san-diego/