Piazza della Repubblica is the center of the city since Roman times. Here, exactly where is the Colonna dell'Abbondanza , the cardo and the decumanus maximi met and there opened the great forum: the Cardo corresponds to via Roma , via Calimala and via Por Santa Maria , instead the Decumano corresponds to via del Corso , via degli Speziali and via degli Strozzi. Archaeological traces have been found at the time of the nineteenth century demolitions, as remains of buildings, of a spa complex to the south, of buildings of worship. Via del Campidoglio and via delle Terme for example were named after the respective archaeological finds. On the southern side there was an entrance arch, while the north side was bordered by a fence wall; to the east and south were public buildings; the Capitoline temple was to the west. In a second moment, probably the Hadrian period, the area was further monumentalized, raising and extending the square, with a new paving in Lunense marble higher than about a meter and a half. There were some doors with steps and a small portico with statues of magistrates and emperors. The Capitolium (1st century BC - 1st century AD) was more or less where today are the arcades, placed on a quadrangular podium of about three meters, accessible by stairs, of which the foundations remain  .
Dante reports the oral tradition that in this neighborhood there was a temple dedicated to Mars that patronized the city: according to the poet this determined the bellicose character of the city. According to other sources a statue of Mars (or another deity, since it was equestrian) would have really existed and would have been placed in the Middle Ages near the Ponte Vecchio , from where it was however swept away during the flood of 1333 .