The St. Marys Town Hall, located at 175 Queen Street East, is on the northeast corner of Queen Street East and Church Street North in downtown St. Marys. The three storey limestone and red sandstone town hall was constructed in 1891.

The property was designated by the Town of St. Marys in 1981 for its heritage value under Part IV of the Ontario Heritage Act (By-law 56-1981).

The St. Marys Town Hall was erected in 1891 on the former site of a two storey hotel that burned down in 1889. The building committee of the day saw the fire as an opportunity to rebuild the Town Hall as a monumental building that would stand the test of time and instil a sense of great pride in the community. The Town Council took heed of this recommendation and the building remains an iconic structure within the Town of St. Marys. The St. Marys Town Hall has operated as the offices for municipal services for well over 100 years.

Built of local limestone with dichromatic red sandstone accents from a plan created by Toronto architect George W. Gouinlock, the hall is composed of a five storey tower, a turret and a smaller body with a gable roofline which abuts both Queen and Church Streets. Characteristic of Richardsonian Romanesque architecture, the hall features round headed windows and arches, rusticated masonry and recessed windows and doorways with contrasting stonework above. Other noteworthy features include the multi arched portico surrounding the entrance on the facade and the checkerboard effect evident on the facade.

Situated on a prominent corner within the downtown area, the Town Hall's tower and roof dominate the St. Marys skyline. The close proximity of the building to the St. Marys Public Library, another heritage building constructed with similar materials, contribute significantly to the strong heritage identity of the downtown area.