One of the Seven Pilgrim Churches of Rome, the Basilica of the Holy Cross in Jerusalem houses several relics from the Holy Land brought to Rome around 325 AD. The relics are said to be parts of the cross from the Passion of Jesus Christ — carried from Jerusalem by the mother of Roman Emperor Constantine I, the St. Empress Helena. The church name comes from the Jerusalem soil that was laid on the floor of the basilica, as a way of moving part of the holy city to Rome. Though it was once the Palazzo Sessoriano, the palace of the St. Empress Helena, it was later converted into a small chapel.
It has since been renovated and restored over the centuries to its Baroque style facade that exists now. Today visitors can see three relics enshrined: pieces of the True Cross, a nail from the crucifixion, thorns from the crown, and small pieces of the tomb of Jesus and the Holy Sepulchre. There is also a full size replica of the Shrine of Turin.
The basilica is a short walk from San Giovanni in Laterano. It is free to enter.