As you walk forward through the side aisle of a Roman church, you will come to the place where the building has two arms which diverge out from the nave. This is the transept. The continuation of the nave beyond this is the apse. Together the nave, transept, and apse, when seen from a floor plan, form a cross.
In the basilica style church, the nave is usually longer than the transept and apse, forming a Roman Cross. In some churches, the nave, transept, and apse are the same dimensions, forming a Greek Cross. Just to keep you guessing, some churches are round, with the altar located opposite the entrance, and niches in place of side chapels. These are usually built within former Roman buildings, such as the Pantheon, which Christians remodeled in 609 ACE to Santa Maria ad Martyrs, and St. Bernardo alle Terme, which used one of the bath structures of the Baths of Diocletian. For this discussion, I will limit us to Roman Cross churches.
The transepts provide additional side chapels spaces, often larger and more ornate that those along the side aisles. The apse is placed behind the baldachin and alter (those get their own discussion later). Often the main mosaics, frescos, and possibly relics are contained there (more on relics later too). If you happen to enter a church that has mass in process, do not attempt to walk forward to look at the transept or apse. Rather, take a seat, enjoy the service, and take in the ambiance from a distance.
Mosaics were used in early churches to decorate the half-round end of the apse. Often these contained images of Jesus, God, Mary, apostles, and the saints related to the church. Two examples are from Santa Purdenziana and her sister’s church Santa Prassede.
This mosaic in the apse of Santa Prudenziana dates to 390 ACE, only 10 years after Emperor Theodosius I had declared Catholic Christianity as the state religion of Rome (Constantine the Great ended persecution of Christians in 313 ACE). Jesus sits on a throne, dressed as Jupiter in a Roman toga. Peter and Paul sit on either side, being crowned by women, representing Jewish and Gentile converts to Christianity. The other disciples sit to either side, though a 16th century restoration hid the two on either far side. The images of the four Evangelists, the eagle, bull, lion, and scribe, hover in the sky above the scene. No longer did Christians have to hide their stories in catacombs. Yet, they drew upon pagan Roman iconography in celebrating their faith.
Santa Prassede had some structure on its location as early as 150 ACE, though the present church was built in 822 ACE. The mosaics in the apse date from this period. Jesus is shown, standing, blessing saints and a flock of sheep below. To Jesus’ right are St Peter, St. Prudenziana, and St. Zeno (he has his own chapel in one of the side aisles). To Jesus’ left are St. Paul, St. Prassede, and St. Paschal. Notice that five of the saints have round halos, but St. Paschal has a square, called a nimbus, over his head. This conveyed that he was still alive at the time of the mosaic. He was the Pope who commissioned the church to be built. Notice the Hand of God above Jesus’ head.
Mosaics were used in the apse of many older churches because the gold and glass tiles picked up the limited light from windows in the nave and candles. To get a better view of these, carry lots of Euros to place into switch boxes near the apse (and some side-chapels) to turn on the lights for a few minutes. This can be a little tricky in larger settings, such as San Paulo Fuori le Mura, which is quiet large and requires trotting nearly 100 feet to the middle of the nave before you can get a good camera angle on the mosaics.
As building techniques progressed, with more windows being added, especially in domes over the transepts, more light allowed frescos to adorn the apse. These often contained scenes from saints lives, rather than the line-up around the apse. The apse fresco in San Croce in Gerusalemme illustrates the discovery of the true cross. Saint Helena, Emperor Constantine’s mother, was rather a collector of memorabilia. She traveled to Jeruselum and came back with lots of Jesus-stuff, including many pieces of the cross on which he was crucified. You skeptics… More on that later, when we get to relics.
The transept provides space for two larger chapels, and occasionally side chapels off from the arms. These may have additional seating facing the nave, or seating facing the art work in the transept. In contrast to the art in the apse, which is usually viewed from a distance, and often partially hidden behind the altar, the mosaics, sculpture and frescos in the transepts is usually prominent, sometimes intimate, sometime overwhelming.
Though actually in a side chapel between the left transept and apse, in Santa Maria del Popolo two paintings by Caravaggio face each other. On the left is the Crucifixion of Saint Peter, and on the right The Conversion of Saul. In between, appears to be an image of the ascension of Mary after her death, which was painted in a different style from Caravaggio’s, and usually overlooked because of the stunning presentation of his works.
In both the paintings of St. Peter and Saul, what I found stunning, being in
the chapel, was how Caravaggio placed us at the ground level of each painting, which is our physical eye-level for both. Thus we are looking from behind one of the labors, who is trying to fasten Peter to the inverted cross. And, we have fallen from our horses with Saul, and are looking up at the light of Jesus, as he asks why we persecute him. Of course for the full effect, about the time you really grasp how powerful these paints are, your Euro-worth of light goes out, leaving you in darkness, just as Saul was left blind. I do not think that Caravaggio planned this, as electricity was not utilized during his life.
One more story about artwork in a transept. While on a tour, our guide mentioned that we should stop by Il Gesu at 5 p.m. for a special event. Each evening, one of the paintings is lowered into the floor, revealing a statue of tomb of St Ignatius, the founder of the Jesuit Order. We arrived a few minutes early, unsure of which painting would move. We relaxed, watching others who walked about or sat in the pews. Some others appeared to waiting as were we. Others appeared unaware or uninterested in the spectacle that was about to happen. At the appointed time, music and commentary (in Italian, thus sound to us) began. Spot lights illuminated various statues in the north transept. The fanfare went on for about 20 minutes. Then the painting began to lower. The much-greater-than-life-size statue of St. Ignatius shone in sliver and gold. This was sort of like a laser-light show for a ’70’s glam-rock band. Churches may be places for quiet reflection, concerts, or the praise band.