An abbey was built at Clones by Tigernach (also known as "Tierney" in English). It was built in the early 6th century. It was dedicated to St. Peter and St. Paul. The ruins of a 12th-century abbey building can still be found in the town. There is also a sarcophagus. They say it was built for Saint Tighearnach after he died. Clones also has a 9th-century round tower and high cross.