Limerick is Ireland's fourth largest city and has a scenic location on the River Shannon just as the estuary escapes into the Atlantic Ocean. If you like culture, then Limerick has it in abundance. It has a varied collection of around 2,000 original works of art including pieces by Picasso and Leonardo Da Vinci. For the heart of Limerick explore the medieval center with the grand 800-year-old King John's Castle and St Mary's Cathedral.