Head up to Northern Ireland for a stop in beautiful Belfast, which, like Dublin, you can spend about a day in. While here, check out Titanic Belfast, a visitor's centre where the RMS Titanic was built. Also head over to Belfast City Hall, Ulster Museum, or take a black cab tour to see the city's political murals and learn about the Troubles, a period of conflict between the city's Protestants and Catholics that lasted from 1968 to 1998.