Once Diocletian’s mausoleum, it had been converted into a Catholic church in the 7^th century. Where the ancient emperor once laid, is now dedicated to Saint Dominius. This is quite ironic, for the Emperor was known to sentence any Catholics to death, and his own burial location became dedicated to the Catholic religion.

Today, the emperor’s current location is not known. He may have been moved, or still where he has been since he died. Today, this church still has 24 columns of red granite. Just as your leaving the cathedral, there stand two wooden doors with 14 images depicting the life of Jesus Christ.

It is considered to be the oldest Catholic Cathedral that remains in use. Though the first part of the building was built in the 3^rd Century, additions came in the 17^th Century, and again in 1100 AD with the bell tower addition.