In 1277 the Cocconato family bought Passerano which thus became part of the consortium, also called the Radicati, which this family linked to the Marquises of Monferrato was constituting in the territory.
The construction of the central part of the castle probably dates back to that period, followed by the fifteenth-century extension and the Mint.
In 1526 the Emperor Charles V sanctioned the autonomy of the Radicati in their county and granted the additional privilege of beating gold and silver coins, a concession which was fully realized only when the state of war ended.
The first coins were issued starting from 1589 by the Mint of Passerano, still existing building, located to the left of the entrance door of the castle enclosure.
One of the first masters of Mint in Passerano was Tommaso Roglia, from Turin, who had contracted, besides the Mint of Passerano, other Mints of Monferrato.
The initial letters "T R" by Tommaso Roglia appear on several coins beaten in Passerano.
In the Mint of Passerano they were mostly counterfeit coins of the great mints; in fact coins of very low alloy were produced, so that the Mint made large sums.
In addition to local coins, Lombard, Venetian, Swiss, German and French coins were imitated in low league.
The mint continued its activity until 1598, the year in which the privilege was revoked by the Duke of Savoy since it continued to mint counterfeit coins.
Civil marriages are celebrated inside the Ancient Mint and it is home to the civic library.