Trinity College’s Book of Kells is Ireland’s most treasured manuscript, an illuminated ninth-century gospel that draws visitors from around the world. A fast-track ticket skips the notorious queue and pairs the Old Library’s breathtaking Long Room with a guided walk through nearby Dublin Castle, seat of power for eight centuries. Your guide brings the cobblestones to life with tales of Viking Dublin and Georgian intrigue. Arrive early; the Long Room is at its most atmospheric before midday.