The layout of the interior takes the shape of a Latin cross. The nave of the Cathedral, which starts from the entrance, is peculiarly long and follows a black-and-white color code. It is trisected into three aisles by a colonnade of hefty stone pillars that are striped in the same colors. One can find statues of allegorical figures and animals on the capitals of these pillars. Where the pillars reach the arches above, a horizontal molding of 172 busts of popes from the 15th and 16th centuries begins tracing the upper ledge of the nave all the way to the presbytery. Below these busts are cornices with the faces of 36 Roman and Byzantine emperors that run parallelly.
Highlights of the Interior of Siena Cathedral
The Nave
The Ceiling and Dome
The Cathedral's ceiling is styled to resemble the heavens, according to the Italian tradition of representing the upper areas of a church as the divine or heavenly realms and the floors as the earthly realms. The vaulted ceiling of the nave is ribbed and studded with yellow stars against a deep blue background with splendid motifs carved into its arches. It then turns into a large dome under the transept. The large hexagonal dome is freckled with small coffers, each containing one star. The drum underneath the dome is encircled with the images and statues of 42 patriarchs and prophets. In the center of the dome, you will find the beautiful glowing lantern designed by Gian Lorenzo Bernini with sunlight falling through it.
The Transept
The transept begins where the nave ends. They (semitransepts) are considered the wings of the Cathedral. In the corners of either transept are two smaller chapels. On the left is the enclosed space of the Chapel of Saint John the Baptist which contains eight stunning frescos of the Life of St. John the Baptist by Pinturicchio. The Chigi Chapel or the Chapel of the Vow is on the right. It is a circular chapel that contains the sacred painting 'Madonna del Voto', a portrait of great importance to the people of Siena. The Tomb of Cardinal Riccardo Petroni, a richly decorated sarcophagus, is an exquisite example of funeral architecture and can be found in the transept as well.
The Presbytery
The presbytery is one of the most sacred parts of the Cathedral. It lies right after the transept and is considered the head of the building. It has a large apse lined with intricate gold motifs indented in it. Painted on the apse are frescoes of the Saints and Paradise by Domenico Beccafumi. Designed by the same artist, are eight statues of angels that act as candleholders, filling the area with warm light. In the oculus above the apse, is a large stained glass window that is a copy of Duccio di Boninsegna’s Life of Mary. The presbytery also holds a magnificent marble high altar created by Baldassarre Peruzzi in 1532.
The Marble Floor
The floor of the Cathedral is often compared to a lushly decorated carpet. This is because large parts of the nave, transept, and chancel are covered with 56 beautiful marble panels. The panels were designed by Sienese artists, with the exception of the Umbrian artist Pinturicchio. They depict scenes from the Old and New Testaments and contain Pagan themes and allegorical figures from classical antiquity. The Ten Sibyls and the She-wolf of Siena in the nave, the scenes of Moses at Sinai in the presbytery, and the hexagonal mosaic of the Lives of Elijah and Ahab in the transept are all must-see panels of the Cathedral floor.
The Gate of Heaven or ‘Porta del Cielo’
The Gate of Heaven is one of the cathedral’s main attractions. It is an elevated corridor of rooms that runs through the nave and encircles the dome of the cathedral. Until very recently, no one has had access to this upper gallery. The Gate of Heaven is symbolically inspired by the Bible's Jacob’s Ladder and was designed to give visitors a spectacular view of the long nave. You also get the clearest view of the vaulted star-spangled ceiling and its moldings and statues from here. This corridor also has an outer component that leads to the terrace of the church.
