The ramparts of Porta Mosa are the remains of the only gate to the city that still exists today, while the other four were demolished in the early 20th century. Porta Mosa is located south-east of the historic centre, in an area called Prato del Vescovo. Originally, the gate connected the new districts of Prato del Vescovo with the countryside and the city's minor river port, called Approdi delle Mose. Next to the gate stands the San Giorgio bastion, built between 1648 and 1653 by Franco-Piedmontese troops during the Thirty Years' War  and completed in 1653.

In the 19th century, Porta Mosa fell into oblivion. Closed and abandoned, it was not demolished, but deteriorated significantly over time. In 1999, the park was redeveloped and transformed into a space for outdoor activities, games and parties. Since then, the park has been the venue for events and concerts during the summer.