Belfast is quaint, traditional, modern, and unimaginable all at once. The people are welcoming, informative, friendly, and always eager to tell a story or suggest a great pub! The tour of the murals is a must for any Belfast traveller and can be visited by foot, cab, or self drive - caution is given to late day touring in these regions due to continued tension betwixt communities.
The Europa is gorgeous, impressive, and just a block from the Opera House - which is a must see as well. And whilst in the neighborhood do step across the street to have a pint and maybe a bite in The Crown Liquor Saloon; it's like walking into history. By all means if Belfast is on your tour list you must see these buildings and take a moment to learn the history behind them - it won't be regretted.
If the nightlife is something you seek, take a journey to The Odyssey which is home to several pubs, clubs, places to eat, and other fun things to do - maybe take in a show while you're there!
Definitely take the time to visit the Titanic memorial and stroll past the Laganside Big Fish with scales of history all over it's body.
Belfast certainly isn't a one-time visit but if you can only go one time (at least for awhile) make sure you don't miss these places. You'll be left with a feeling of awe at the beauty and history that Belfast holds.