Above is the representation of a medieval siege on military fortifications.

Historians have different opinions as to the presence of an elevating bridge whereas there is documentation as regards the presence of sluice-gates lifted by chains and pulley systems.  The gates still bear the signs of pivots and holes used for the bars that closed the gates.

Above is the Guidoriccio da Fogliano; Below is the representation of the 1554 siege at Monteriggioni when the Castle was surrendered by treason.

-         Below is a picture of Monteriggioni dating back to the XVIII century.

Below is the statute of Monteriggioni; As in “statutes of the commune and man of Monteriggioni” in the year 1380, the defenders and inhabitants of the Castle were considered “Citizens of Siena”.     

The Castle of Monteriggioni was built in 1213 on Mount Ala and its construction took 6 years.  It was built around a Longobard farm with money given by the Republic of Siena to bar the way to Florentines in the long battles between the two cities. The building of a castle ex novo represented a novelty in the expansive politics of the city of Siena.  In fact, the Republic had formerly bought pre-existing castles such as that of Quercegrossa.  Therefore, the Republic of Siena acquired the land of the nobleman of Staggia and then built the Castle on it. 

The Circular Walls are of an elliptic shape, are 570 metres long and 2 metres thick.  The 15 towers measure 6x4 metres and rise 15 metres above the circular walls.  The walls had square battlements and “bertesche”.  “Bertesche” are wooden structures that protruded out of the walls as a defence mechanism whenever the castle was under attack.  The Castle was also surrounded by “Carbonaie”. These was moats filled with carbon that were lit during attacks from the enemiesa.   

There were 2 entrances to the Castle: the east entrance overlooking Siena - called “Porta Romea” or “Porta Franca” - and the west entrance overlooking Florence, which is diametrically opposite the first entrance and known as “Porta Fiorentina” or “Porta di San Giovanni”.         

In Porta San Giovanni one can see signs of another medieval structure known as “Rivellino”, which is an additional rectangular structure put before the main entrance having an elevating bridge or a second gate.

Probably the Sienese meant to build a Castle bearing in mind the battle they had won against the Florentines next to Monte Ala in 1145 because the Castle is now built on this hill.  The Sienese and the Florentines fought for the possession of Monteriggioni in 1244 and 1254.  In 1269, after the battle of Colle - immortalized by Dante Alighieri in canto XIII of Purgatory - the defeated Sienese found refuge in the Castle of Monteriggioni while the Florentines tried to attack the castle in vain.

After the plague of 1349, the Sienese left a captain and his soldiers in Monteriggioni with the scope of cleaning the area from the evil-doers that ransomed the poor people.  There is a story that relates how the inhabitants had once caught four criminals in the act, then forced the captain in garrison at the castle and took justice in their hands by hanging all four of them.opo la peste del 1349 i Senesi tennero a Monteriggioni un capitano con soldati  allo scopo di ripulire la zona dai malfattori che taglieggiavano la povera gente , si racconta che gli abitanti dopo aver sorpreso in fragranza di reato quattro delinquenti , forzando la mano del capitano che era di guarnigione al castello, fecero dei 4 giustizia sommaria impiccandoli.

Between 1400 and 1500 the walls were lowered to cater for the military’s exigencies due to the artillery, and the “carbonaie” were filled with earth.

In 1526 the Florentines besieged Monteriggioni with 2000 infantry and 500 horsemen beating the walls with the artillery.  The Castle resisted and on the 25^th of July the Sienese beat the papal army – the Florentines’ ally – in the battle of Camollia, and in so doing they also managed to free the Castle from the Florentine’s siege.

On the 27^th April 1554, Monteriggioni was surrendered by treason to the Marchese di Merigliano by Captain Zeti who was ready to suffocate the liberty of the Republic of Siena as happened in 1555.  With this treason, Captain Zeti, who then became a Florentine, surrendered the otherwise unconquerable fortress and cut through the Sienese’ defensive system which was made up of the small forts of Castel Petraio, Monte Auto, Quercegrossa and Chiocciola.  The inhabitants of Monteriggioni were taken to Florence as slaves and nothing more could be found about them.  Despite the fact that Monteriggioni was conquered, it was not enough to damage its reputation as an unconquerable fortress.