A further renovation was undertaken from 1999 to 2000 and a third courtroom a judge's chamber, jury deliberation room, library, and holding cell for defendants were added.

The equally well-known architectural firm of Proudfoot, Rawson, Souers & Thomas of Des Moines was selected to provide input and oversight to the project.

A site on the block bounded by Douglas, Pearl, Sixth, and Seventh streets was purchased for $270,000, and approximately $725,000 was spent on construction; in all, the costs totaled $100,000 less than anticipated.

When postal services moved to a new facility on Jackson Street in 1984, the building interior was modified to create additional office space and a new courtroom.

Courthouse is a skillful blend of the Stripped Classical and Art Deco styles of architecture, a combination that was commonly used for federal building design in the 1930s.

The mixture adopted traditional classical forms of architecture while abandoning excessive ornament in favor of more subtle stylized decorative components that are typical of the Art Deco style.

The building rests upon a five-foot base of granite quarried from Pine Mountain, Iowa, while the remainder is clad in light gray limestone ashlar from New Bedford, Indiana.

The entrances on the Sixth Street elevation are flanked by fluted pilasters with carved limestone capitals featuring a stylized eagle motif, which alludes to the federal presence.

The lobby is finished with light gray polished marble on the floors and walls, which are topped by an elaborate painted entablature with sunrise and chevron designs.

An elaborate coffered plaster ceiling with leaf and dolphin designs is located in the courtroom, and original bronze pendant light fixtures are also present.