Architect William Strickland of Philadelphia designed the capitol and thought it was his greatest achievement. It was built between 1845 and 1859 by skilled artisans and by convict and slave labor. It has been used continuously since 1853.
It was built mostly of limestone quarried nearby, and it was one of the first buildings in the United States to use iron as a structural element. It is one of eleven state capitols with no dome. When it was completed it was the tallest building in the southeastern United States. Its cupola is modeled on the Choragic Monument of Lysicrates.
During the Civil War the building was a camp for Union troops, a hospital and a lookout. Strickland, who died before it was finished, and Samuel Morgan, who oversaw construction, are entombed in its walls. The tombs of President James K. Polk and his wife are on the grounds.