Walk atop the Old City’s famous 17th-century walls, listen in at Saint Columb’s Cathedral and lift a pint at a pub. Whether you call it Londonderry or just Derry – the correct name, like most things here in Northern Ireland, being a subject of much debate – this town is a noted time capsule. Its mile of surrounding walls has never once been breached since 1618, and a guided walk along their 26-foot-high summit gives you a mapmaker’s vantage point on Derry’s still-visible medieval street plan. You’ll also have a great view of the Guildhall, a Gothic stunner sitting just outside the walls – with a clock tower that would give Big Ben a serious run for his money. At Saint Columb’s Cathedral, you’ll hear the organist rock the ancient stone walls with a rendition of that Irish favorite “Londonderry Air” – known more widely as “Danny Boy.” In the cathedral’s Chapter House Museum, see fascinating artifacts including the huge padlocks to Derry’s original city gates. Later, you’ll toast the day with a drink at a local pub before heading out for an hour or so of free-range wandering time before the ride back to the pier.