Whithorn Priory Museum

This is an early Christian site in Scotland that was used as such from the 5th or 6th century. There are graves that are dated to this period and archaeological findings suggest that a monastery complex may have been built in the late 6th century. It is certain that the monastery was built in the 8th to 9th centuries. Local tradition names Saint Ninian as the founder of the monastery and widely credited with bringing Christianity to the region. His shrine was a popular pilgrimage destination in the Middle Ages. Some people believe that this place is the cradle of Christianity.

The excellent museum underlines this

This large stone was carved in the 7th century and does not have the intricate pattern seen on later carved stones. It once stood on the island of Withorn and bears (as far as I could decipher) the inscription "Petri prima Apostoli" (below the cross).