Earning the title of The Oldest Pub In Ireland, and perhaps soon The Oldest Pub in the World, Sean's Bar's history is a fascinating tale. Sean’s Bar has a detailed and documented history right back to 900AD. During renovations in 1970, the walls of the bar were found to be made of "wattle and wicker" dating back to the ninth century. Old coins which were minted by various landlords for barter with their customers were also found. The walls and the coins are on display in the National Museum. One section remains on display in the pub. Sean’s Bar has been researched thoroughly by the Guinness Book of Records and proudly holds the record for "The Oldest Pub in Ireland" with an official dating of 900AD. Research is ongoing into the title of "The Oldest Pub in the World"; so far, nothing older has been found.

St Ciarán founded his monastery on the banks of the River Shannon in the 6th Century. The monastery flourished and became a great seat of learning, a University of its time with students from all over Europe. The ruins include a Cathedral, two round Towers, three high crosses, nine Churches and over 700 Early Christian graveslabs. The original high crosses, including the magnificent 10th century Cross of the Scriptures are on display in a purpose built visitor centre adjacent to the monastic enclosure.