[3] The first county seat was Marietta, located a few miles northwest of Marshalltown, and the first courthouse was built there.

The citizens of Marshall, as the town was then called, wanted the county seat moved there so they had a courthouse built free of charge.

The two-story brick building with a stone foundation measured 60 by 40 feet (18 by 12 m), and was built by hundreds of people from the community.

In 1881 citizens of Marshall County voted for a $100,000 courthouse to be built on the public square in Marshalltown deeded by Henry Anson.

During the Great Depression and war years, taxpayers could not afford to pay for needed repairs, so the building began to deteriorate.

[8] The Friends of the Courthouse Committee, a newly formed organization, decided to save the building.

[6] The courthouse was damaged in a tornado on July 19, 2018, which ripped the spire from the top of the building's cupola.

In the center is a high square limestone tower with a clock, dome, and small cupola at the top.