The building originally measured  by , but an extension in 1922 gave it its current dimensions. The unique façade of the Old Slave Mart consists of  octagonal pillars at each end, with a central elliptical arch comprising the entrance.
The building initially had a specific size, which was later expanded upon in 1922. This expansion resulted in the current dimensions. The distinctive façade of the Old Slave Mart is characterized by octagonal pillars at each end, with an elliptical arch serving as the main entrance.