The complex is Italianate style in design and comprises four rectangular sections connected by three arcaded passageways.
 The grouping is 244 feet (74 m) wide on Royal Street, 275 feet (84 m) long on Church Street, and the back is 213 feet (65 m) wide on Water Street.
 The building is stucco over brick construction with wood trim and brackets.

The two central sections form a U shaped mass, fronted on Royal Street and extend to Water Street.
 They are two floors in elevation on Royal Street and one floor in elevation on Water Street.
 This central section is crowned with a central octagonal cupola.
 The two annex wings are also two floors in elevation, although of lesser height than the central sections.
 The south wing annex is 30 feet (9 m) wide by 275 feet (84 m) long and faces Church Street.
 The ground floor of the south wing once housed stalls and shops for the market, but has since been altered to enclose the space.
 The north wing annex is 30 feet (9 m) wide and is much shorter in length than the south wing.
 The north wall is attached to the neighboring Gulf Coast Exploreum.
The complex is Italianate style in design and comprises four rectangular sections connected by three arcaded passageways.  The grouping is 244 feet (74 m) wide on Royal Street, 275 feet (84 m) long on Church Street, and the back is 213 feet (65 m) wide on Water Street.  The building is stucco over brick construction with wood trim and brackets.
The two central sections form a U shaped mass, fronted on Royal Street and extend to Water Street.  They are two floors in elevation on Royal Street and one floor in elevation on Water Street.  This central section is crowned with a central octagonal cupola.  The two annex wings are also two floors in elevation, although of lesser height than the central sections.  The south wing annex is 30 feet (9 m) wide by 275 feet (84 m) long and faces Church Street.  The ground floor of the south wing once housed stalls and shops for the market, but has since been altered to enclose the space.  The north wing annex is 30 feet (9 m) wide and is much shorter in length than the south wing.  The north wall is attached to the neighboring Gulf Coast Exploreum.
Old City Hall (Mobile, Alabama)