The Cathedral Quarter is where Belfast's nightlife and cultural life converge in the most interesting way. Hill Street, Commercial Court, and Donegall Street form the core, cobbled and narrow, lined with Victorian buildings that have been turned into bars, music venues, and independent spaces without losing too much of what made them interesting to begin with.
Black Box is here. The Dirty Onion is here. The Spaniard is tucked in a side street. The MAC Belfast anchors the cultural end. The murals on the gable walls are political and sharp. Come in the afternoon to walk it in daylight and get a sense of the architecture; come back in the evening when the whole thing shifts gear.
This is the part of Belfast that visitors remember. Not because it's been packaged for them, but because it hasn't been entirely, and you can still feel the city working through something.