The piazza, enlarged in 1408, underwent further alterations until the end of the 16th century. Originally protected by wooden porticoes, the piazza was used as a market space for meat, oil and grains, as well as a meeting place for assemblies and rallies.
At the centre of the piazza is a statue of the merchant Francesco di Marco Datini (1335-1410), made by Antonio Garella in 1896.
The piazza is also home to the famous bronze fountain of Bacchus, depicting the god of wine as a young boy sitting atop bunches of grapes. The current version is a copy of the original by Ferdinando Tacca, which is today housed in the atrium of the municipal offices.