Perhaps it was Mondonio's family who wanted to build a castle in this town. According to oral tradition, already at the end of 1100 on the hill of Mondonio there was only one fortification, while the village remained located at the bottom next to the church of Raseto.
Therefore, the geographic-political situation in a certain period of the Middle Ages appeared to be the following: Mondonio and Pino d'Asti governed by local seigniories, then subjected to the Marquises of Monferrato, bordering the county of Cocconato governed by the Lords of Radicata, also allies of the Monferrato and with Castelnuovo, linked to the Republic of Asti.
Thus, we can easily understand the defensive position in which our border fief had to be located, so much so that it had to provide for the construction of a strong castle.
From the few remains that have come down to us, we can hypothesize that Mondonio was surrounded by at least two walls, within which stood the castle with several towers and a chapel. A door to the second enclosure was located, according to De Canis (in his Corografia Astigiana, 1814), just before the current oven.
Just as a deep moat encircled the manor, following its bed the streets of S. Rocco, Cavallone, Turco, then flowing into the current Piazza Balbo precisely into a large pond, which until the mid-800 could still be seen.
Another tower had to rise where the terrace of the parochial house is now located and another one near the Piasset's house next to the bowling alley.
Few are the vestiges of the field handed down to us: a part of a wall of the castle in via Cavallone, the foundations of the parish house, in which there are fragments of a tower and several parts on which the present castle is founded including mighty walls with loopholes and ancient windows.
Then there is the tower next to the castle, located right on the highest point of the village, built, according to some, in the first part of 1160. It is a lookout tower that perhaps also served for signaling. It has no external access but only two windows and several loopholes; you get there through a basement connected to the sign today completely impractical.
There are innumerable wells and tunnels, some bricks, which populate the top of the hill. Who knows where all these undergrounds carry? Certainly someone gave access to the open country, the only way out-and-out of safety, when the castle was besieged. And we know that many times Mondonio was set on fire by his enemies.
One of the bastions that controlled the first city wall was located at the end of Via Giunipero, in the place called “courtyard of the Peila”. And another, of configuring the features, was located at the top of Via S. Rocco.
Given this approximate reconstruction, it appears that Mondonio had to present itself in those times as a strong castle with towers, battlements, bastions that certainly gave a hard time to the attackers. The almost total destruction of this fortification occurred in the late 1400s.