Built to train the clergy in accordance with the precepts of the Council of Trent, it was inaugurated in 1637 by Bishop Lorenzo della Robbia and, two years later it was given its Costituzioni or disciplinary rules by Pope Urban VIII. It was added to in 1697 by Bishop Filippo Neri Altoviti and again by Bishop Luigi Maria Strozzi in 1726.

The building with its east-facing façade and regular squared layout stretching north to south closes in the “lawn” of the cathedral in piazza Mino, probably up to where the Roman forum ends below ground archaeological discoveries were made as works proceeded.

The seminary grew to become the most important training centre of the territory of Fiesole and as such it remained until the late twentieth Century. It gave an education not only to all the priests of the Diocese but also to many young people who were to follow a non-religious career.  In the nineteenth Century it acquired scientific equipment for educational purposes and then Angelo Maria Bandini bequeathed his precious library to it. Today in the Episcopal Seminary there are wonderful contemporary and ancient works

The church , situated on the highest point of Fiesole and erected over the ruins of a pagan temple of the “auguri”, probably was built by Teodorico  in the VI century a. C. with the name of “Santo Pietro in Gerusalemme”. Here in the year 823 a.C. was buried  the Bishop Sant’Alessandro, who claimed a right to the local Church  from the Emperor Lotario to whom later the church was dedicated.

The original aspect of the church is almost lost, but the interior has preserved the original basilican plan with three naves separated by columns with capitals taken from the classical buildings of Fiesole.

It stands opposite the main entrance of the Cathedral and is reached via a double nineteenth-century staircase. Its construction goes back to the eleventh century, but between the fifteenth and the seventeenth centuries it underwent various transformations and enlargements.

The present façade dates back to the year 1600 and bears the imposing coat-of-arms belonging to Bishop Filippo Neri Altoviti. Inside, in the Bishop's private chapel, visitors can admire frescoes by Ghirlandaio's school, whereas in the palace's former oratory, the Chapel of St. James the Greater, are conserved an important fresco, the “Coronation of the Virgin Mary”, attributed to Bicci di Lorenzo, and a collection of liturgical artworks in gold that belonged to the Diocese of Fiesole.

Le Mura di Fiesole (The Walls of Fiesole) represent the ancient defense system of the citadel and can be traced back to the Etruscan age, around the 4^th century B.C.
Built with enormous square blocks of sandstone (so big that a popular belief in the Middle Ages said that they were created by giants), from the caves in the surrounding areas, at the beginning they acted as a massive protection against the attacks of Romans who, after conquering Fiesole and turning it into their colony, used them again and reinforced them.The ancient Etruscan walls remained still until the Lombard period and also during the Middle Ages, with a view to achieving proper defense also against the attacks of Florentines. However, after conquering Fiesole, in 1125, the Florentines began to partially destroy the walls.
Even today one may see the remains of the enclosure wall on the Eastern, Southern and Northern sides of the city.The best preserved site can be seen in the North, on the suggestively named street (via Mura Etrusche), separating the archaeological area.Other remains can be seen on the San Francesco hill, to the upstream of the public garden. Here, according to some experts, the more irregular and rough features can make us think of a fortification that was prior to the urban enclosure and whose aim was to protect the acropolis.
Some other remains can be found in the surroundings of Borgunto, to the South, in Frà Giovanni Angelico and in the neighbourhood of the former Monastery of San Girolamo.However, the position of the access gates has not been recognized with certainty, even though some researchers speak of a Northern gate (at the crossroads between via delle Mura Etrusche and via di Riorbico), an Eastern gate (in Borgunto) and a Southern gate (via Vecchia Fiesolana).    

Facing the Seminary on the eastern side, stands the building erected by the government of Lorenzo dei Medici as the headquarters of a suburban city government for the territory of Fiesole and now the seat of the municipal government.
The colonnaded portico and the small loggia, both in local pietra serena, are of the original building. Both the inner and outer walls feature the coats of arms of the local ruling elites from the 16th to the 18th Century.
From 1800 to 1900 in the town hall were located the public school, the king police and the archeological museum. The municipal government made this its headquarters only in 1910.