The Old St. Louis County Courthouse was built as a combination federal and state courthouse in St. Louis, Missouri. Missouri's tallest habitable building from 1864 to 1894, it is now part of the Jefferson National Expansion Memorial.

The Federal style courthouse was completed in 1828. It was designed by the firm of Lavielle and Morton, the first architecture firm west of the Mississippi River above New Orleans. In 1839 Henry Singleton remodeled it in the Greek Revival style, with four wings, including an east wing that comprised the original courthouse and a three-story cupola dome at the center. In 1851 Robert S. Mitchell began a redesign of the courthouse in which the east and west wing were remodeled. In 1861 William Rumbold replaced a cupola with an Italian Renaissance cast iron dome modeled on St. Peter's Basilica in Vatican City. The St. Louis dome was completed in 1864. (wikipedia.org)