Born in 1775, Daniel O’Connell was a 19th century Irish nationalist leader. Despite permanent Catholic organizations being illegal at the time, O’Connell set up a series of mass meetings to petition for Catholic freedom. He died of brain softening in 1847 while on a pilgrimage to Rome. He is famously known for his dying wish where he quoted “my body to Ireland, my heart to Rome, my soul to heaven”.
His body is buried in the Glasnevin cemetery in Dublin (which you can go on a tour to see). His heart, placed in a sliver casket, was sent to the Irish College in Rome and put into the chapel of Sant’Agata dei Goti. A marble monument was placed above it. However, when the Irish College moved O’Connell’s monument as part of a reorganization, his heart was missing.
Some people claim his heart was built into the marble monument itself but nevertheless, his heart has never been found and remains one of the biggest secrets of the church.