Dating back perhaps to late Roman times, this square acquired great importance in the Middle Ages, although it was very different, closed to the east by the San Silvestro Church and open towards the Cathedral.
The Palazzo dell'Arengo was built in 1204. Beneath its spacious portico justice was decided, and in the immense hall with mullioned windows on the first floor meetings of the Civic Assembly were held.
The ground floor of the Palazzo della PodestÓ, from the 14th century, probably opened onto a portico. The entrance on the shorter side had an arch with the arms of the city's new rulers, the Malatesta. The present building is the result of restoration carried out from 1919 to 1925 by Gaspare Rastelli.
The square's central feature, the fountain, attracted merchants and travellers. The square is seen in a portrayal of the city in the Malatesta Temple.
The fountain, admired and cited by Leonardo da Vinci on 8 August 1502, is still a focal point of the square. It was once surmounted by a statue of St Paul, replaced in the 19th century by the pineapple decoration that gives the fountain its present name.
Work on the Palazzo Garampi, now the City Hall, started in the early 1500's. To give unity to the civic buildings facing onto the square, the San Silvestro Church, near the main street (Corso d'Augusto) was demolished, and the western side was closed by the building of the public bakeries. These were replaced by the "Vittorio Emanuele II" theatre, now renamed "Amintore Galli", built between 1843 and 1856 to designs by Luigi Poletti and inaugurated with Verdi's Aroldo in 1857. The theatre was seriously damaged in the last war.
Since 1625 a statue of Pope Paul V has stood at the centre of the square, erected by the city authorities.
The Old Fishmarket, opened in 1747 and built to designs by Francesco Buonamici, demonstrates the economic importance of the fishing industry.