This is the 31st year of the National Lottery Dublin Marathon, which is run through the historic Georgian streets of Dublin, Ireland's largest and capital city. Dublin is home to a quarter of the country's almost 4 million people. Though founded by the Vikings, it is now a vibrant, dynamic city where half of the population are under 25. Dublin is only an hour by air from most U.K. and European cities, and more than half of the expected entry of 10,000 will be made up of overseas runners, many of whom will be returning to sample Irish Hospitality once more.