Erected towards the end of the 13th century, the ancient town hall, known as the Arengario (from the Latin arengarius, derived from the Germanic hari-hring, "place for assemblies") stands in a position almost contiguous to the cathedral, signifying also visually the opposition of powers, religious and civil, that also in Monza distinguished the communal period.
Situated in the city center, in relation to the vast Market Square and in axis with the main street that linked the city to Milan and Brianza, it was part of a complex ensemble, which building events and restorations have reduced to just the town hall. Next to it stood, connected by a suspended passageway, the palace of the praetorian (or podestà), which has now disappeared.
The building has a large arched portico on the ground floor, supported by massive stone pillars, a place for meetings and exchanges, and a single large covered hall with wooden trusses on the second floor, intended for meetings and assemblies, which opens with a small balcony loggia (the "parlera") from which decrees issued by the municipality to the population were read. The bell tower, built later, on the north side, has Ghibelline swallowtail battlements.
