This is the actual Cathedral of Rome and is where the cathedra of the Pope is.
The main relics in this Church are pretty important.
The main one is a part of the table from the Last Supper which is high above the Eucharistic Chapel in the left trancept.
The other major relics are up in the top of the baldachino over the papal altar.
The two statues of Saint Peter and Saint Paul hold the heads of these two Saints.