Located in the heart of the historical town, in medieval times the square was the political center of the city, as well as one of the main places of exchange, along with the nearby Piazza del Ferrarese.

The square is surrounded by buildings belonging to ancient families of Bari, and the Palace of the Seat of the Nobles, ancient meeting place of the noble people of Bari.
Icon and symbol of the square is the famous column "of justice", once used to bind and expose to the public fraudulent debtors.

Today Piazza Mercantile is one of the most popular and active squares in the city.