With multi-million dollar bars popping up downtown on what seems like a weekly basis, Casey’s Irish Bar & Grille continues to do what it always has done (well, for the past 35 years or so, anyhow): Pour frothy imported beers, serve traditional Irish food and present a steady stream of classic rockers. With pressed-tin ceilings, high-backed wooden booths and a massive mahogany bar, the subterranean bar evokes Dublin or London rather than Los Angeles. It goes without saying that the biggest day of the year here is St. Patrick’s Day, which means green beer, house-cured corned beef and plenty of drunken revelry for all.