Caltech's 124-acre (50 ha) primary campus is located in Pasadena, California, approximately 11 miles (18 km) northeast of downtown Los Angeles. It is within walking distance of Old Town Pasadena and the Pasadena Playhouse District and therefore the two locations are frequent getaways for Caltech students.

In 1917 Hale hired architect Bertram Goodhue to produce a master plan for the 22 acres (8.9 ha) campus. Goodhue conceived the overall layout of the campus and designed the physics building, Dabney Hall, and several other structures, in which he sought to be consistent with the local climate, the character of the school, and Hale's educational philosophy. Goodhue's designs for Caltech were also influenced by the traditional Spanish mission architecture of Southern California.

During the 1960s, Caltech underwent considerable expansion, in part due to the philanthropy of alumnus Arnold O. Beckman. In 1953, Beckman was asked to join the Caltech Board of Trustees.^[1]: 282 In 1964, he became its chairman.^[1]: 275 Over the next few years, as Caltech's president emeritus David Baltimore describes it, Arnold Beckman and his wife Mabel "shaped the destiny of Caltech".^[1]: 288

The Beckmans made a major gift to Caltech in 1962, when they funded the construction of the Beckman Auditorium, a concert hall designed by architect Edward Durrell Stone. When the circular white stone hall opened with a gala concert on February 25, 1964, it was praised for its acoustics.^{[1]: 289–291 [2]}

The auditorium was the first of several expansions at Caltech that the Beckmans supported. In 1974, the Beckman Laboratory of Behavioral Biology (BBB) was dedicated.^[1]: 291 The building was seen as a significant step towards the establishment of a new program focusing on neurobiology and a multi-leveled understanding of brain and its mechanisms at the chemical, cellular, and systems levels.^{[3]: 153–154} On April 25, 1986, the Beckman Laboratory of Chemical Synthesis was dedicated. The Beckmans' gift supported not only the building, but also the installation of state-of-the-art scientific instrumentation in six customized laboratories.^[4] Finally, the Beckmans funded the Beckman Institute, a multi-disciplinary center for research in the chemical and biological sciences. In 1986, Beckman agreed to donate $50 million towards the institute and its endowment. Designed by architect Albert C. Martin, Jr. in a Spanish style, the Beckman Institute was dedicated on October 26, 1989, and opened in 1990.^{[1]: 275–290}

In 1971 a magnitude-6.6 earthquake in San Fernando caused some damage to the Caltech campus. Engineers who evaluated the damage found that two historic buildings dating from the early days of the Institute—Throop Hall and the Goodhue-designed Culbertson Auditorium—had cracked. These were some of the first reinforced concrete buildings, and their plans did not contain enough details (such as how much reinforcing bar had been embedded in the concrete) to be sure they were safe, so the engineers recommended demolition. However, demolishing these historic structures required considerably more effort than would have been necessary had they been in real danger of collapse. A large wrecking ball was used to demolish Throop Hall, and smashing the concrete revealed massive amounts of rebar, far in excess of safety requirements. The rebar had to be cut up before the pieces could be hauled away, and the process took much longer than expected.

New additions to the campus include the Cahill Center for Astronomy and Astrophysics and the Walter and Leonore Annenberg Center for Information Science and Technology, which opened in 2009,^[5][6] and the Warren and Katherine Schlinger Laboratory for Chemistry and Chemical Engineering followed in March 2010.^[7] The Institute also concluded an upgrading of the South Houses in 2006. In late 2010, Caltech completed a 1.3 MW solar array projected to produce approximately 1.6 GWh in 2011.^[8]

This list includes buildings and facilities of California Institute of Technology.^[11] The listing does not include off-campus/co-owned properties. Demolished buildings are shown in grey.