was their most famous project. In this period, Gill trained Hazel Wood Waterman who helped with a group of houses built near Balboa Park for socialites Alice Lee and Katherine Teats. Waterman later went on to become an architect with her own practice. After California passed a law requiring architects to obtain a certificate in 1901, Gill was automatically granted a certificate because his practice was already in operation. In 1903, Gill was appointed to a special seat on a Chamber of Commerce committee to build the U.S. Grant Hotel, which was ultimately designed by Harrison Albright, despite Hebbard & Gill's submission of designs to the committee. In 1907, Gill was accused of unauthorized work on a sewer line, causing a clog. Gill denied the accusations, but his partnership with Hebbard was damaged beyond repair. Less than a month later, Gill entered into a partnership with Frank Mead, who had been a Hebbard & Gill employee. The partnership lasted seven months, and completed only a few houses. Gill designed the Broadway Fountain, also known as the Electric Fountain, in 1908, for the center of Horton Plaza Park, in Downtown San Diego. Though designed in the prime of his Modernist period, its revivalist style is atypical of his work. Gill's design was chosen in a competition among professional architects, and was one of the first projects in the country to combine water and colored electrical light effects. In 1911, Gill's nephew, Louis John Gill, joined his firm as a draftsman. That same year, Gill lost an important commission for the Panama-California Exposition (1915) to Bertram Goodhue. He did work for a time as an associate of Goodhue, including the design of the Balboa Park Administration Building, Balboa Park's first structure, which is located just outside the California Quadrangle. Today, it is known as the Gill Administration Building of the San Diego Museum of Man, and houses offices and the Gill Auditorium. Gill was commissioned by Ellen Browning Scripps in 1913 to design the La Jolla Woman's Club. In its construction, he used a "tilt-slab" construction technique to assemble the exterior arcade walls on site. The result is California's first tilt-up concrete building. These walls integrate hollow, clay-block infill to lighten the slab's weight. For the interior walls and central "pop-up" volume, however, he employed conventional balloon-frame construction. Though Gill is often associated with the tilt-up method, he used it in only