Although there are no documents to attest this, the primitive core of the palace is said to have been built in the 15th century as the residence of Cicco Simonetta, councillor of Francesco Sforza.

[2] In 1607, hunted down, the nobleman Gian Paolo Osio, lover of the nun of Monza and author of several crimes, took refuge here: he hoped to find hospitality with the Taverna family, who instead treacherously killed him in the basement of the palazzo.

In 1908, on the death without heirs of Luigi Isimbardi, the palace was sold to the industrialist Franco Tosi, from whom in 1935 the province of Milan purchased it, making it its seat.

[6] On the garden front, the palace has a neoclassical façade with a rusticated ground floor, with the central body surmounted by a monumental timpanum.

[7] The interior decorations are noteworthy, especially those in the Sala degli affreschi with works by Morazzone, in the Sala del consiglio with the fresco of the Apoteosi di Angelo della Vecchia nel segno delle virtù by Giambattista Tiepolo, in another room the Episodio dei Visconti by Francesco Hayez.