St. Sylvester was the first Pope of Rome to reign entirely under the liberty of the Church, guaranteed by the Edict of Milan in 313. He was the son of a Roman, called Rufinus and, according to the Liber pontificalis, was elected to the See of Peter in 314. During his reign, the city began its transition into its Christian era, with the construction of the great Constantinian basilicas - including the Basilica of St. Peter on the Vatican Hill, which was erected above a temple dedicated to Apollo, to mark the burial place of the first Bishop of Rome.

St. Sylvester and Emperor Constantine collaborated on the Lateran Basilica and Baptistery, which were built adjacent to the former imperial palace where the Pontiff lived, as well as the (Roman) Basilica of the Holy Cross in Jerusalem, and the Basilica of St. Paul. Pope Sylvester’s memory, however, is most closely tied to the church of St. Martin and Sylvester, which still stands in Rome’s Monti neighbourhood.

Pope Sylvester did not attend the First Council of Nicaea in 325, where the Nicene Creed was formulated, but he was represented by two legates, Vitus and Vincentius, and he approved the council's decision.

His faith so moved his contemporaries, that they publicly honoured him as “confessor”, i.e., one who, though not suffering martyrdom, lived a life completely given to Christ. Pope Sylvester also contributed to the development of the liturgy. It was most probably during his reign that the first Roman Martyrology was composed, and his name is associated with the creation of the ancient Roman school of sacred song.

Pope St. Sylvester is patron of the chivalric order called the Militia Aurata, or “of the Golden Spur”, which was founded by Emperor Constantine I in person. After various events throughout the centuries, in 1841, Pope Gregory XVI, separated the Order of Pope St. Sylvester from the Militia Aurata, assigning to the Order of St. Sylvester particular statutes and decorations.

In the West, the liturgical feast of Saint Sylvester is on 31 December, the day of his burial in the Catacomb of Priscilla. This is now the last day in the year and, accordingly, in German-speaking countries and in some others close to them, New Year's Eve is known as Silvester. In some other countries, too, the day is usually referred to as Saint Sylvester's Day or the Feast of Saint Sylvester. In São Paulo, Brazil, a long-distance running event called the Saint Silvester Road Race occurs every year on 31 December.

Other Saints of the Day
1. Saint Barbatian
2. Saint Donata
3. Saint Hermes
4. Saint Melania
5. Saint Zoticus