The Medieval Cassero, originally called 'Corridor of the Cassero', namely the corridor to the Castle, was built in the mid-14th century by the Florentines immediately after the subjugation of Prato, in order to connect the small fortress erected near the Fiorentina Gate to the Eastern Gate to the Emperor's Castle, the location of their garrison.
The high covered walkway, a long corridor originally 230 metres long, used to connect the walls to the 'Cassero', that is, to the Castle, and it was not accessible to the city, thus serving a double defensive function: from external attacks but also from possible revolts by the people of Prato, who had been only recently conquered. The passageway enabled the soldiers to reach the castle directly from the city walls and it represented a safe way for the Florentine troops to enter and exit the city without being seen by the people of Prato.
The internal walkway, raised 3 metres above the street, consists of a long corridor with barrel vault and, on either side, lunette windows alternating with narrow slits that give light to the passageway.
The Cassero remained unchanged in function and shape until the 16th century, after which it was gradually abandoned. Recently the structure has been carefully restored and reopened to the public. Today the Cassero represents a fascinating location in the historical centre, where one can enjoy sweeping views of the Emperor's Castle and Prato's skyline. The recent renovation, completed in 2000, has made it possible to recover two sections of the old structure and restore a walkway that begins in via Pomeria and ends on viale Piave, near the Castle. The medieval Cassero, an example of successful architectural restoration, today is also used as a venue for photography and painting exhibitions. The latter represent a sign of our times within the ancient medieval walls and offer visitors a unique experience.