From: 'Guide to Saint Peter's Basilica'
On the back wall is the Altar of Our Lady of Succor, embellished with the rarest alabaster, amethysts and other semi-precious stones, and four superb columns of African marble and green porphyry, the work of G. Muziano (1528-1592). It is called after the 12th-century fresco framed above the altar, brought here by Gregory XIII in 1578. The remains of St. Gregory of Nazianzus (d. 390), one of the great theologians from Cappadocia, are preserved in a porphyry urn beneath the altar. He is shown in the spandrels, together with St. Gregory the Great, St. Basil the Great and St. Jerome.

From: 'Seminarian's Guide'
This contains one of the few paintings in the basilica: actually, it is an icon because it is painted on wood. The altar was built by Giacomo della Porta.

Here lie the remains of St. Gregory of Nazianzus (d. 390) - one of the great Cappadocian Fathers, who helped clarify the wording of the mystery of the Holy Trinity.

In the spandrels, Nazianzus together with St. Gregory the Great, St. Basil the Great, and St. Jerome.

When Christians fell under the domination of Muslim masters, they often found themselves in slavery when they refused to renounce their faith. Christians would sometimes cooperate to raise funds to buy these slaves their freedom, often under the patronage of Our Lady of Succor - Our Lady, Help of Christians.