From Ned Devine’s in Herndon to the Old Brogue in Great Falls to Galway Bay in downtown Annapolis, the Irish pubs are going to be packed with revelers making the most of St. Patrick’s Day, kicking off an unofficial three-day weekend. Friendly advice: No matter where you’re going, try to arrive as early as possible. Lines usually start building in the afternoon, and no one wants to wait outside while friends are enjoying themselves indoors.