Dating back to the 7th century, the Cathedral of Saint Domnius, often referred to as Sveti Dujam by the locals, is arguably the most important building in Split, Croatia. This church is said to be the oldest Catholic cathedral in the world, due to it maintaining its original structure without major renovations. The cathedral is made up of the church, dedicated to the Virgin Mary, and the bell tower, dedicated to Saint Domius, patron saint of Split.

Compared to the church, the bell tower is its younger cousin, dating back to the 12th century. This cathedral is quite possibly one of the history's most pertinent examples of irony. Diocletian, a 3rd century Emperor, and hater of Christians, was responsible for the death of Saint Dominus. Guess where Diocletian's mausoleum used to be? That's right – where the Cathedral of Saint Dominus now stands.