Ireland’s third largest city was founded by Vikings who settled at the mouth of the River Shannon in 922 C.E. Walk the pleasant streets or along the banks of the Shannon, and enjoy the historic buildings, cozy pubs, modern restaurants, and cosmopolitan vibe that make the city so vibrant. Spend a couple of hours at the Hunt Museum for its collection of art and antiquities, including works from Picasso, Bronze Age shields, and 18th-century ceramics. Visit King John’s Castle, which was built for King John in 1200 and whose curtain walls and five drum towers are an impressive sight from across the river, and Limerick's oldest building, St. Mary’s Cathedral on nearby Bridge Street, which dates back to 1168. If you’re in the city on a weekend, head to the Milk Market, in operation since 1852, for artisan foods, fresh produce, crafts, and other market finds.