Since its completion, the 175-foot-high tower of this early Beaux-Arts building has dominated the community. The 1884–1886 courthouse building was the third one to be built within the county. The first was a small wood structure built in 1851 in Marietta. When the county offices were moved to Marshalltown, a second, two-story brick courthouse was built, in 1857–1858. John C. Cochrane, who designed the third building, was responsible not only for the initial plans for the Illinois State Capitol (1867–1883), but for a number of courthouses in Illinois and Indiana. Stylistically the Marshall County Courthouse was an advanced design for the mid-1880s, anticipating the surge of interest in the Beaux-Arts Classical tradition which developed in the 1890s. The scheme of the building is that of a central rotunda that reaches upward to a dome contained within the base of a central tower. The high tower is open on its lower level, above which are four clock faces and then a segmented dome and tall, thin lantern. During the 1950s and 1960s various proposals were made to replace the existing courthouse with a new building, but these proposals were rejected by county voters. In 1974 funds were voted by the residents of Marshall County to restore and update the building, a project carried out by the Des Moines firm of Wagner, Marquart and Wetherell.