Ikea Feast of the Chair of St. Peter, February 22

The actual relic, the Chair of St. Peter, is in St. Peter's Basilica in Rome. The Latin word for cathedra refers to the seat or throne for a  bishop. The one in Rome is enclosed in a gilt bronze casing. Inside the casing is a wooden throne that was used by St. Peter (although Wikipedia says it was a gift from the Holy Roman Emperor Charles the bald to Pope John VII in 875 A.D.

  The apse is at the end of the central nave. In the center is the Altar of the Chair of Peter, a masterpiece which is unmistakably the work of Gian Lorenzo Bernini (1598-1659).
Every year on February 22, the Church celebrates the feast of the Chair of St. Peter, to commemorate St. Peter's teaching in Rome. Already in the second half of the 18th century an ancient wooden chair inlaid with ivory was venerated and traditionally held to be the Episcopal chair on which St. Peter sat as he instructed the faithful of Rome. In fact, it is a throne in which fragments of acacia wood are visible, which could be part of the chair of St. Peter, encased in oak and reinforced with iron bands. Several rings facilitated its transportation during processions. Pope Alexander VII commissioned Bernini to build a sumptuous monument which would give prominence to this ancient wooden chair. Bernini built a throne in gilded bronze, richly ornamented with bas-reliefs in which the chair was enclosed: two pieces of furniture, one within the other. On January 17, 1666 it was solemnly set above the altar.
The base of the altar is made of black and white marble from Aquitaine and red jasper from Sicily. Four gigantic statues (about 5 m. tall) in gilded bronze surround the Chair which looks almost as if it were suspended amidst the clouds. The two outer statues are figures of two Doctors of the Latin Church: St. Ambrose and St. Augustine; the two inner statues, with bare heads, are of two Doctors of the Greek Church: St. Athanasius and St. John Chrysostom. These saints represent the catholicity of the Church and at the same time, the consistency of the theologians' teaching with the doctrine of the Apostles.

The Catholic Encyclopedia says:

We conclude, therefore, that there is no reason for doubting the genuineness of the relic preserved at the Vatican, and known as the Cathedra Petri.

Father Z says the cathedra is decorated with candles on one day each year...today.