The earliest extant record of the island is from the year 999, when it was identified as Isola di Sant’Angelo, referring to a chapel dedicated to Saint Michael found within its castle. In the middle of the twelfth century the island was in the possession of counts belonging to the Barbavara di Gravellona family. The Borromeos made various attempts to obtain the Isolino di San Giovanni in the late sixteenth century with the aim of establishing a Barnabite college.
The earliest documented account of the island dates back to 999, when it was referred to as Isola di Sant’Angelo, describing a chapel dedicated to Saint Michael within its castle. In the mid-twelfth century, the island was held by counts from the Barbavara di Gravellona family. The Borromeos made several attempts in the late sixteenth century to acquire the Isolino di San Giovanni with the goal of establishing a Barnabite college.