This city on the Shannon River has a rough and tumble past of poverty and grime that was captured by Frank McCourt’s best-selling novel "Angela’s Ashes." However, today’s Limerick is successfully polishing its image, and it was designated Ireland’s first National City of Culture in 2014. Two of Limerick’s must-see historic sights are King John's Castle, which reopened in 2013 after extensive renovations, and St. Mary’s Cathedral, which was founded in 1168 by the king of Munster.