O’Fallon Technical High School

A four-story Mid-century Modern building of brick construction with ribbon windows separated by glass-block spandrel panels and buff concrete banding. Variegated dark red and gray stone panels, set in a checkerboard pattern, clad the entrance tower, which is capped by a flagpole. A tall brick chimney rises above the roofline near the building's center. The building occupies a large campus with an attached athletic field, running track, and stadium lighting.

The St. Louis Board of Education built O'Fallon Technical High School at 5101 McRee Avenue as a replacement for Hadley Technical High School (1931), from plans by architect F. Ray Leimkuehler. The Board voted at its June 22, 1954 meeting to close both Hadley Technical, which served white students, and the Booker T. Washington Vocational School, which served Black students, consolidating their programs into the new building. The reassignment of students took place on February 14, 1956, with the district redistricted so that both O'Fallon and a reopened Hadley Technical received students. The school was named for John O'Fallon (1791–1885), a St. Louis philanthropist. An annex was added to the building in 1970. In August 1992, the school reopened as the Gateway Institute of Technology, a magnet high school established in response to a federal court order mandating a high-technology magnet program as part of the district's desegregation plan. It was renamed Gateway STEM High School — for Science, Technology, Engineering, and Mathematics — in June 2012.