(Collecta: S. Mennas)
(Image source)
(Image source)
From Blessed Ildefonso Schuster's, The Sacramentary:
Today's station is held at St. Paul's because he is the prototype and model of catechumens, on account of his conversion on the way to Damascus...
The ceremony is also known as in aperitione aurium, because the miracle which Christ worked upon the deaf man was renewed in a spiritual sense upon the candidates for baptism, to whom the Pontiff explained for the first time with solemn rites the Creed, the Lord's Prayer and the beginning of the four Gospels. Thus the ears of the catechumens, deaf hitherto to the words of truth, were opened at length to hear the tidings of eternal life.
From the Churches of Rome wiki:
After his execution, St Paul was buried in a cemetery at this site, about two kilometres from the city walls by the road to Ostia. A shrine, or cella memoriae, was soon erected, and many early Christians came to venerate the Apostle.
The first church here was, according to the Liber Pontificalis, built by Emperor Constantine and consecrated on 18 November 324. It was a small church, built over the grave of St Paul. Between 384 and 386, Emperors Valentinian II, Theodosius and Arcadius demolished the church and built a large basilica. The architect was Cyriades. According to the inscription on the triumphal arch, it was consecrated in 390 by Siricius, and completed in 395 under Emperor Honorius. Although heavily restored, not least after it was damaged by fire, the present basilica looks much the same as it did in the 4th century.
Pope St Leo the Great (440–461) started restoring the church. About 50 years later, Pope St Symmachus (498–514) ordered the reconstruction of the apse, which was unsafe. Several more restorations and changes were carried out, under Pope St Gregory the Great (the transept), Pope Sergius I (the roof and some rooms), Pope Hadrian I (the aisles and atrium) and Pope Leo III (the transept, roof and floor, and added apse mosaic).
In 883, the walls and tower encircling the church were completed. This was knows as the "Johannipolis" (in Italian Giovannipoli), or "City of John" after Pope John VIII, and was built to protect the church from Lombards and Saracens. The defence works were tested in 1083–1084, when they withstood several attacks by Emperor Henry IV.
Fire broke out in 1115, and Pope Innocent II had a wall with columns built in the transept to support the unsafe roof. The transept was divided into two aisles by this wall.
Disaster struck again in 1349, when an earthquake badly damaged the basilica and destroyed the bell-tower and part of the portico. Pope Clement VI had the damages repaired.
Major restorations started under Pope Boniface IX, when he allowed all donations to the church to be used for repairs. Pope Martin V continued the work, and in 1426 the work was intensified under the rector of the church, Gabriele Condulmer, later Pope Eugene IV.
In 1653 Francesco Borromini designed plans for a total restructuring of the church. Due to a lack of funds, only the roof was changed under Pope Clement X.