Feast of the Dedication of St. John Lateran

St. John Lateran, Feast of the Dedication of

November 9This Roman Catholic observance commemorates Pope Sylvester's consecration of the Basilica of the Most Holy Savior, commonly known as St. John Lateran, in Rome on November 9, 324. Churches as they are known today—that is, buildings set apart as places of worship—did not exist for the first two centuries of the Christian era; believers gathered in each other's homes. Thus, the pope's public dedication of this church at the beginning of the fourth century was a first in Christianity and merited a special celebration.
St. John Lateran began as the mansion of a wealthy Roman family named Laterani until it was given to the Christians, serving as the residence of popes for a thousand years. The home was built around a great hall, and this hall became the church. It was called a "basilica," a word that originally described an oblong hall, rounded at one or both ends, where public assemblies were held. A baptistry was added and dedicated to St. John the Baptist, and since the 12th century, the church has been known as St. John Lateran.
SOURCES:
DaysCustFaith-1957, p. 285
RelHolCal-2004, p. 105