St. Petersburg High School, founded in 1898, is a secondary school in the Pinellas County School District in St. Petersburg, Florida. The school's current building, a historic landmark, was built in 1926. It was designed by Missouri architect William B. Ittner. It was listed on the National Register of Historic Places in 1984. The school was billed as the nation's first million dollar high school. The school previously occupied several other historic locations around St. Petersburg, including a location at Mirror Lake (1919–1926).

William Butts Ittner was an American architect in St. Louis, Missouri. He designed over 430 school buildings in Missouri and other areas, was president of the St. Louis Chapter of the American Institute of Architects from 1893 to 1895, was awarded an honorary degree by the University of Missouri in 1930, served as president of the Architectural League of America during 1903–04, and at the time of his death was president of the St. Louis Plaza Commission, a fellow and life member of the American Institute of Architects, and a thirty-third degree Mason. He was described as the most influential man in school architecture in the United States and has a star on the St. Louis Walk of Fame. He was appointed St. Louis School Board commissioner in 1897 and is said to have designed open buildings that featured "natural lighting, inviting exteriors, and classrooms tailored to specific needs." In 1936, Ittner died. His legacy is survived by the William B. Ittner, Inc. and Ittner & Bowersox, Inc. architecture firms in St. Louis.