A Guide to
​St Peter's Basilica

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The Transept

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The two arms of the transept are identical in design. Each arm has a single bay with a semi-circular apse; each apse contains three chapels. 

Altar of St Joseph

Left Arm
The central altar of the apse was originally dedicated to the apostles Simon, Jude and Thaddeus, whose relics are preserved in an ancient sarcophagus. It is now dedicated to St. Joseph. The altarpiece is by A. Funi (1890-1972). 

On the right is the Altar of Saint Thomas. The altarpiece is by Vincent Camuccini (1771-1844). The relics of Pope St. Boniface IV (r. 608-15), who consecrated the Pantheon, are kept beneath the altar.

On the left is the Altar of the Crucifixion of Saint Peter. The altarpiece is a copy of a painting by Guido Reni (1575-1642). According to tradition, St. Peter was martyred precisely where the altar stands. Part of the basilica is actually built on the site of Nero's Circus, the putative location of St Peter's death. 

The eight statues in the niches depict saints who founded religious orders or institutes. Starting on the right side and moving anti-clockwise: 

St Juliana Falconieri, Servite nuns (Paolo Campi, 1740).
St Angela Merici, Ursulines (Pietro Galli, 1866).

St Norbert, Norbertines (Pietro Bracci, 1767).
St William of Vercelli, Williamites (Giuseppe Prinzi, 1878)
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St Peter Nolasco, Mercedarians (Paolo Campi, 1742).
St Louise de Marillac, Daughters of Charity (Antonio Berti, 1954).

St John of God, Brothers Hospitallers (Filippo Della Valle, 1745).
St Euphrasia Pelletier, Sisters of the Good Shepherd (Giovanni Niccolini, 1940).

The four allegorical stucco statues in the spandrels of the arches represent: Vigilance & Liberality (right) and Purity & Benignity (left). 

The metre-high inscription, which runs round all three walls, reads: O PETERE DIXISTI TV ES FILIVS DEI VIVI AIT IESVS BEATVS ES SIMON BAR IONA QVIA CARO ET SANGVIS NON RELEVAVIT TIBI. The text is adapted from the Gospel of St Matthew (16:16-17):  'He saith unto them, But whom say ye that I am? And Simon Peter answered and said, Thou art the Christ, the Son of the living God. And Jesus answered and said unto him, Blessed art thou, Simon Barjona: for flesh and blood hath not revealed it unto thee' (KJV). 

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Right Arm
The right arm of the transept is reserved for confession, which is available in a number of languages. In 1869, the First Vatican Council met here.  

The central altar of the apse is dedicated to St Processus and Martinian, who, according to legend, were the jailors that St Peter baptised when he was in prison. The chapel on the right is dedicated to St Wenceslaus, while the one on the left is dedicated to St Erasmus.   

The eight statues in the niches depict saints who founded religious orders or institutes. Starting on the right side and moving anti-clockwise: 
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St Cajetan, Theatines (Carlo Monaldi, 1738).
St Francesca Xavier Cabrini, Missionary Sisters of the Sacred Heart (Enrico Tadolini, 1947).

St Jerome Emiliani, Clerks Regular of Somascha (Pietro Bracci, 1756).
St Joan Thouret, Sisters of Charity (Enrico & Carlo Quattrini, 1949).

St Joseph Calasanz, Piarists (Innocenzo Spinazzi, 1755).
St Bonfilius Monaldi, Servites (Cesare Aureli, 1906).

St Bruno, Carthusians ( Michelangelo Slodtz, 1744). 
St Paul of the Cross, Passionists (Ignazio Jacometti, 1876).

The four allegorical stucco statues in the spandrels of the arches represent: Justice & Faith (right) and Prudence & Hope (left). 

The metre-high inscription, which runs round all three walls, reads: DICIT TER TIBI PETRE IESVS DILIGIS ME CVI TER O ELECTE RESPONDENS AIS O DOMINE TV QVI OMNIA NOSTI TV SCIS QVIA DILIGO TE. The text is adapted from the Gospel of St John (21:17): 'He saith unto him the third time, Simon, son of Jonas, lovest thou me? Peter was grieved because he said unto him the third time, Lovest thou me? And he said unto him, Lord, thou knowest all things; thou knowest that I love thee,' (KJV).

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