The Marion County Courthouse is a beautiful Neoclassical-style building erected in 1901. It features architectural elements typical of the style including Corinthian columns, and a portico. In the center is a large octagonal dome that is topped with an octagonal lantern. The courthouse was the only one built in Hannibal and remains in good condition today. It was designed by well-known Kansas City architect James Oliver Hogg and added to the National Register of Historic Places in 2002. The courthouse is actually one of the two courthouses in the county; the other is in Palmyra, which is the county seat. This situation is the result of the establishment of a court of Common Pleas in 1844 in Hannibal.