In 1867, Canadian immigrant Prudent Beaudry (who had arrived in 1852 following his brother Victor) acquired most of an uninhabited hill near downtown Los Angeles, named it Bunker Hill and sold lots to wealthy families interested in building luxury two-story Victorian homes. After his death, a short cable railway opened in 1901 to carry people to the top of the hill, the "Los Angeles Incline Railway" (today's "Angel's Flight").

The immigrants expected life in Los Angeles to be different from life in their towns and cities of the East. Those who came with money expected to live in grand extravagant buildings. Among the spectacular mansions of Bunker Hill were the Brunson Mansion, built in 1882 by Anson Brunson, a former judge who had been hired as a lawyer by the Santa Fe Rail Road, and the Potts Mansion, built in 1886 by James Wesley Potts (who had arrived in 1852 via the Overland Trail, started out as a fruit vendor but became rich buying land) and acquired in 1887 by silver-mining magnate Lewis Bradbury. (The Brunson Mansion was demolished in 1917 and the Bradbury in 1929).

Those who came with less money were attracted by a new kind of house, the "bungalow", a little box with a porch surrounded by a garden, an idea imported from British India that worked well in Los Angeles' hot climate and gave the middle class a sense of privacy that was hard to get in the cities of the East.

Another high-class neighborhood sprang up on Crown Hill, just west of Bunker Hill. In 1885 three businessmen, Henry Witmer (a Wisconsin banker who had moved to Los Angeles in 1884), Edward Hall (the son of a 49er who had founded a San Francisco auction house, first acquired by Henry Mayo Newhall and then turned into the Newhall's Sons and Company) and Jesse Yarnell (a newspaperman who in 1881 had gained control of the newly established Los Angeles Times), purchased Crown Hill, which at the time was a desolate land, then subdivided the property into 1400 lots and finally built a cable railway (modeled after the San Francisco one) to connect it with downtown, the Second Street Cable Railway, notable for the steepest gradient of North America. Crown Hill soon became a fashionable district, its homes auctioned by Newhall’s Sons. In 1887 San Francisco architects Samuel and Joseph Newsom, who had just completed the jewel of Victorian houses in California, the Carson Mansion in Eureka, built for Witmer the so-called Witmer Bank Block, a four-story Romanesque building that in 1888 became the headquarters of a new bank, the California Bank, with Henry Newhall (of Newall's Sons) as president.

In 1888 a retired Arizona judge named Charles Silent acquired a plot near the University of Southern California and in 1899 he created an upscale subdivision called Chester Place. The first residents were the mining baron Oliver Posey and his socialite wife Sarah (a painter, musician and amateur architect), who had moved from Wisconsin to Los Angeles in 1893, and who hired Theodore Eisen and his new partner Sumner Hunt to build an opulent mansion resembling a chateau. That home was purchased in 1901 by oil baron Edward Doheny. By 1903 there were twelve mansions in Chester Place.

Nearby was "Millionaires Row", a string of mansions owned by millionaires. It started when in 1890 Chicago lumber tycoon Thomas Stimson decided to retire in Los Angeles and commissioned architect Carroll Brown to build a 30-room mansion. Stimson used the same architect for the Stimson Block, an office building on Spring Street that opened in 1893, the first six-story building in Los Angeles and therefore the tallest.

The boom of the 1880s made Los Angeles proud enough to erect grandiose buildings such as the County Courthouse, completed in 1891 by Theodore Eisen (demolished in 1936), and the Hotel Nadeau, built in 1882 by Remi Nadeau, the first four-story building in the city and even boasting the city's first elevator. In July 1888, Asher Hamburger (who had moved from Sacramento in 1881) opened the Peoples Store in Phillips Block, next to City Hall, the second four-story structure in Los Angeles, designed by Burgess Reeve in the French Renaissance Revival style. In 1908 his heirs A. Hamburger & Sons opened the "Great White Store", the largest department store west of Chicago, a city within the city (it even hosted the post office and the public library). Another four-story building was erected in 1886, an addition to the Pickit Villa of Donald and Katie Pickit, who then turned it into a fancy hotel, the Bellevue Terrace Hotel. A five-story office building, designed by Sumner Hunt, was erected in 1893 for gold-mining tycoon Lewis Bradbury.

The Boston merchant Joseph Winchester Robinson, who had moved to Southern California in 1882 to invest in orange groves, opened a "Boston Dry Goods Store" which in 1895 his heirs expanded into the vast department store J.W. Robinson’s, designed by Theodore Eisen and Sumner Hunt and located opposite City Hall.

Two of Los Angeles' most important department stores were founded by Toronto immigrants, who both arrived (independently) in the 1890s. Arthur Letts (an Englishman) arrived in 1894, opened The Broadway in 1896 and moved it in 1915 to nine-story building. John Bullock arrived in 1896 and was one of his early employees, and in 1907 Letts financed a new department store, an upscale one called Bullock's, which in 1923 (when Letts died) became an independent business.

Already aware of earthquakes and with plenty of space to build, Los Angeles eschewed from the beginning the high-rise building. In 1905 a city ordinance limited the height of a building to "150 feet" (about 50 meters).

The area around Spring Street became the "Wall Street of the West".

Spring Street is where architect John Parkinson opened his studio in 1894. An apostle of the Beaux Arts classicism which had become fashionable after Daniel Burnham's large-scale Beaux-Arts buildings at the 1893 Chicago Columbian Exposition, Parkinson designed the steel-frame Homer Laughlin Building (1897), the Susana Machado Bernard House (1901) in the Art Nouveau style, Los Angeles’ first skyscraper, namely the Braly Block (1902), the eight-story luxury Hotel Alexandria (1906), which became the heart of Spring Street, and the Rosslyn Hotel (1914), the city’s biggest hotel yet.

Architects were inspired by landscape painter Dana Bartlett's book "The Better City" (1907), which envisioned Los Angeles as the prototype of the "City Beautiful" movement that originated from the "Garden City" movement in Britain and from Burnham's work at the Columbian Exposition.

One of the precursors of the "City Beautiful" movement had been Frederick Law Olmsted, the first major landscape architect of the USA, who had designed Central Park in New York City with his partner Calvert Vaux (1857), and then many other landscapes including the campuses for UC Berkeley (1866) and Stanford University (1886), as well as the World's Columbian Exposition (1893). In 1902 his son Frederick Jr worked with Daniel Burnham on the masterplan for Washington's monumental area. In 1913 New York-based banker Frank Vanderlip purchased the old Mexican land grant Rancho de los Palos Verdes, in the south of Los Angeles, and hired Frederick Jr and his brother John to develop it for affluent residents.

The "City Beautiful" movement even spread to the realm of the dead. Hubert Eaton took over the graveyard of Tropico, north of downtown Los Angeles (and now part of Glendale), and in 1917 turned it into the first Forest Lawn Memorial Park, inspired by Renaissance parks, which soon became a chain of graveyards. Blacks, Jews and Chinese were not admitted.

During the years of the multiple booms, from 1880 to 1920, Los Angeles became a laboratory of urban and architectural experiments driven by the new wealthy class.

The Mission Revival style or Spanish Colonial style was largely the invention of Arthur Page Brown, first with his California Building at the World Columbian Exposition of 1893 and then with the five "Crocker Row" houses in Santa Barbara, commissioned in 1894 by William Crocker (son of railroad baron George Crocker). By the turn of the century the Mission Revival style became popular among resort hotels, like the Potter Hotel of 1901 designed by John Austin, and even for train stations. All sort of secular buildings borrowed architectural elements of the Spanish missions of the colonial era. The style influenced Elmer Grey's Beverly Hills Hotel (1912) and Julia Morgan's Los Angeles Examiner building (1913), built for William Randolph Hearts, which was the world's largest building for a newspaper. Frederick Jr and John Olmsted designed the Palos Verdes community (that was started in 1913) and Lilian Rice, another pioneering female architect, designed the planned community Rancho Santa Fe in San Diego (1922) in the Spanish Colonial Revival style.

Bertram Goodhue popularized the Spanish Colonial Revival style with his El Prado Quadrangle in San Diego's Balboa Park for the 1915 Panama–California Exposition, notably the California Building in the form of a Roman basilica. The influence of that project was felt throughout California. That style helped cement the myth that California was the Mediterranean of the USA. The more sophisticated Mediterranean style of the following decade was mastered by San Diego architects Richard Requa and Frank Mead, who in 1917 designed the Ojai community northwest of Los Angeles and in 1919 the Bailey House in LaJolla; and by George Washington Smith, who settled in Montecito, near Santa Barbara, and built his own "Casa Dracaena" (1917), which inspired countless others, followed by the "Casa del Herrero" (1925) for St Louis industrialist George Fox Steedman, and "La Toscana" (1927) for New York banker Kirk Johnson, married to Genevieve Joyce (heiress of John Joyce), both in Montecito. The Colonial Revival style culminated in William Mooser's Santa Barbara Courthouse (1929). The Colonial Revival merged with Modernism in the work of San Diego architect Irving Gill, who designed the St James Chapel in La Jolla (1908) and the Walter Dodge house in Los Angeles (1916).

The "Arts and Crafts" movement that had originated in Britain with intellectuals such as William Morris and John Ruskin took roots in Los Angeles.

Charles Lummis, a Harvard dropout and poet who, hired in 1884 by the Los Angeles Times, walked from Ohio in 143 days to his new job writing weekly dispatches for the magazine. In 1886 he spent two months at a fort in Arizona covering the campaign to capture the legendary Apache rebel Geronimo. From 1895 he edited the magazine Land of Sunshine (renamed Out West in 1902) which attracted artists, writers and free thinkers to Los Angeles. In 1895 he spearheaded the formation of Los Angeles' Landmarks Club for the preservation of the old Spanish missions and Mexican adobes, a move that would influence California's architecture. A self-taught ethnographer in the company of anthropologist Adolph Bandelier, he invented the idea of a cultural "Southwest”. The first museum in Los Angeles was the Southwest Museum that he opened in 1907 in downtown Los Angeles at the main station of Henry Huntington's Pacific Electric. His home El Alisal, built between 1898 and 1910 by himself using local river stones and help from indigenous laborers, became the center of a burgeoning community of bohemian artists and writers who were escaping the traditions of the Eastern states and searching for a new alternative lifestyle. That home spread the Arts and Crafts philosophy to the Arroyo Seco neighborhood between Los Angeles and Pasadena.

Masters of the Arts and Crafts style were Irving Gill, who designed the Marston House (1904) in San Diego, and especially the brothers Charles and Henry Greene, who designed the Gamble House (1908) in Pasadena, built for a wealthy Ohio retiree, David Gamble, heir to the fortune of the James Gamble (who had formed the famous company with William Procter).

Irving Gill coined a stripped-down style with his 1908 buildings: the five-story Cabrillo Hotel and the Scripps Institution of Oceanography, both in La Jolla. They predate both Peter Behrens' "Turbo factory" (1909) in Berlin and Adolf Loos' "Steiner house" in Vienna (1910).