The castle of the round tower stood in Como is on the site of the current Teatro Sociale di Como. It was built in 1250 by the Ghibellines Rusconi, lords of Como of the time. The castle was intended to strengthen the authority of the nobility, common to many buildings of the period such as the Castello Sforzesco in Milan. Around the original nucleus the castle grew in proportion to the increasing power of the Rusconi, who acquired complete control over the city’s political life between the end of the thirteenth century and the beginning of the following century. In 1288 the walls were raised up to the lake and the moat was reinforced.
In 1335 the castle of the round tower passed to the Visconti family, in the year in which Como became the dominion of the powerful Milanese family; they enlarged it and inserted it into the wider Cittadella Viscontea or a fortified area of the city from scratch, which included the Bishopric, the churches of Santa Maria Maggiore, San Provino and San Giacomo as well as the city Broletto and the port of the emperor. Over the centuries it was used as a base for the various troops stationed in Como, depending on the different foreign domination that occupied the city of Como and Lombardy. Spanish, French and Austrian garrisons alternated, which modified the complex several times according to military requirements. The castle was demolished in 1811 when the city authorities agreed with the owners of the small patrician theater of the city. The prefect exchanged the palace with the area of the old castle of the city; the transfer of the castle also allowed the notarial archive of the Broletto to be transferred.
The transfer resolution was approved on January 31, 1809, under the presidency of Alessandro Volta and with the only vote against the Marquis Giuseppe Rovelli, historian of the city and owner of a part of the building. On 28 January 1813 the Social Theater was inaugurated. Neoclassical style. The perimeter walls of the castle have been rebuilt and limit the Social Theater and the area of the rear arena.