Zook operated out of Chicago, working with his nephew D. Coder Taylor, whom he considered his protege.

"[3] Coder Taylor described that it was changed to a "much more Art Deco type of design than it was at the outset".

[3] Quoting the Architectural Record March 1941 issue: "This building was planned for an individual who then donated it to St. Charles at the time of its dedication.

"[4] Coder Taylor remembered his client, Col. E. J. Baker, "who was a millionaire as a result of inheriting quite a lot of money from Bet-a-million Gates."

In its design and construction, both Col. Baker and Coder Taylor wanted the building to last, to stand through time and to age gracefully.

[5] The building's design was inspired by the Art Deco movement, but its architectural style has been characterized as Moderne.

[1][5][6] The National Register nomination characterizes it as Moderne rather than Art Deco due to the fact that it "is an example of the phase of design after 1930 in which buildings were drastically stripped of surface ornaments and windows were grouped in bands.

"[1] Its exterior features white Georgia "Cherokee" marble and a base of black granite, with prominent motifs of "faceted surfaces, zigzags, chevron patterns, and octagon shapes".

[1][6] The Municipal Building has served continuously as the seat of local government in St. Charles since its dedication in 1940.

In order to comply with the Americans With Disabilities Act, a new entry atrium was constructed in 1995 to provide the building with an elevator.