The church used to be the palace of Saint Helena who was the mother of Constantine the Great. She was one of the early Christians and is said to have brought back the cross of Jesus to Rome and other sacred relics like the Scala Sancta which was the stair in Pontus Pilates house where Jesus walk up on the way to his trial. After her death it was transformed into a basilica. This original basilica fell into neglect but was restored by Pope Lucius II in the 12th century. The church was further modified during the 16th century and got its current facade during the middle of the 18th century.
The inside of the church is lavishly decorated – but unlike many of the other churches in Rome the Santa Groce isn’t famous for the art works inside the church. Instead it is known for its extensive collection of important sacred relics. The relics is on display in the basement to get there you need to leave the main church and walk through some halls until you get to the rooms where the relics are on display.
The most important pieces are the ones Saint Helena brought back from Jerusalem where she had been on a pilgrimage. She brought some wood which is claimed to originate from the cross of Jesus, a couple of thorns from his rose crown and a nail from the cross. In addition to these relics there are others from a later period.