Most of the apostles and lots of saints have their own feast day, but there is no “Feast of St. Peter.” Today (February 22) the Church celebrates the “Chair of Peter” the sign that Peter was the first among the apostles and the one designated to lead the early Church after Jesus’ Resurrection and Ascension. For the record, Peter is not alone. St. Paul does not have a “Feast of St. Paul.” We celebrate these great saints together in a single celebration, the Feast of Sts. Peter and Paul.
What is the Chair of Peter? It depends on what you mean. On the one hand, there is a physical object–an ancient, ornamented chair–located in the apse of St. Peter’s Basilica. On the other hand, there is the spiritual authority that this chair represents.
The actual chair has been changed (modified, repaired, given ornamentation) over the ages depending on the aesthetic tastes of the reigning pope – but it is believed the original chair has been preserved. How original – hard to say – but tradition holds that it was used by St. Peter. More likely it was a gift from Holy Roman Emperor Charles the Bald to Pope John VIII in 875 CE. Scientific inquiry concludes all the materials date no earlier than the sixth century. Time has taken its toll, as have relic collectors.
Well before the sixth century this feast was celebrated in Rome on January 17th and February 22nd. Early martyrologies recognize two physical chairs that had been used. Pope John XXIII consolidated the two celebrations into the current feast.
What is more important is the spiritual significance of the feast the Church celebrates today. According to Pope Benedict:
This is a very ancient tradition, proven to have existed in Rome since the fourth century. On it we give thanks to God for the mission he entrusted to the Apostle Peter and his Successors. “Cathedra” literally means the established seat of the Bishop, placed in the mother church of a diocese which for this reason is known as a “cathedral”; it is the symbol of the Bishop’s authority and in particular, of his “magisterium”, that is, the evangelical teaching which, as a successor of the Apostles, he is called to safeguard and to transmit to the Christian Community. . . .The See of Rome, after St Peter’s travels, thus came to be recognized as the See of the Successor of Peter, and its Bishop’s “cathedra” represented the mission entrusted to him by Christ to tend his entire flock. . . .Celebrating the “Chair” of Peter, therefore, as we are doing today, means attributing a strong spiritual significance to it and recognizing it as a privileged sign of the love of God, the eternal Good Shepherd, who wanted to gather his whole Church and lead her on the path of salvation [General Audience, Feb. 22, 2006].