If you're passing through Belfast on a whistle-stop day trip, join the open top bus tour (see Tours) for a one-hour scoot round most of the major sights.
Belfast City Hall, Titanic Belfast, Botanic Gardens, Queen's University, Crumlin Road Gaol and the Shankill and Falls Roads are all on their route, as is a brief diversion into Stormont Estate and Harland & Wolff shipyard, home of the big yellow cranes and birthplace of Titanic.
If you have time to spare, and don't see it on the tour, catch a N°4 Metro Bus for the 15-20 minute journey to the Stormont Estate where you can gaze at one of the city's most iconic buildings and take a leisurely stroll around its manicured grounds.
Another great outdoor location and stunning city backdrop has to be Cavehill. Head north on Metro Bus N°1, jumping off at Belfast Castle for unrivalled views across the city.