It is formed by two distinct building , the Fortress , built under PERSON@1 I de ' Medici -LRB- NUMBER@1 -RRB- , and the Cassero -LRB- late 15th century -RRB- , the latter used as military jail until NUMBER@2 .

The PERSON@2 a castel , built under PERSON@1 I de ' Medici the castel was used as military jail until NUMBER@2 .
