Founded in 1947 by Herbert W. Armstrong, Ambassador College became the headquarters of the Worldwide Church of God, formed by consolidating various lots within a four-block area, incorporating structures dating from 1905 into the 1920s. The architectural and planning firm Daniel, Mann, Johnson and Mendenhall (DMJM) was hired in 1963 to develop the campus master plan and Garrett Eckbo was later invited to revise the plan for the campus.
Several main features comprise the existing campus, including the eclectic Merritt House East Garden with a cypress allee that leads down to an existing Renaissance-inspired pool, traversed by an Oriental-style bridge designed by Eckbo; the Mayfair Villa Campus Mall designed by merging five existing gardens, connected by a cascading stream; and the Kate Fowler Estate Lower Garden, a small formal garden with pergola, fountain, lawn and a Roman-style tempietto designed by Paul J. Howard.
Ambassador College closed in the 1980s. Ambassador Auditorium (DMJM, 1972) is now the Harvest Rock Church. Maranatha High School now occupies the southeast quadrant. In late 1990s, the City of Pasadena formulated the West Gateway Specific Plan to encourage development, preservation and reuse of the west campus site.