O'Neill's St Mary Street

You'll find yourself on St Mary Street, Cardiff's main drinking artery, where O'Neill's stakes its claim with an unmistakably Irish accent. The place has that warm, wood-lined cosiness that makes you want to settle in for longer than you planned, all creaky floors and the kind of lighting that doesn't make you regret your life choices at 11pm. It's the sort of pub where locals actually drink—not just tourists ticking boxes—with a proper bar team who know what they're doing. The Guinness is always spot on, and if you're here during a match, the atmosphere shifts into something properly electric.