Take a modern-day ringer for Vivian Leigh, with a voice like an Irish Ella Fitzgerald, back her with a swing band, and then place them in one of Brooklyn’s most beautiful historic buildings. What do you get? Tara O’Grady and The Black Velvet Band performing at Green-Wood Chapel on Saturday. The band plays traditional Irish music set to a swing jazz beat, as well as jazz standards. It’s the perfect anecdote to the usual St. Patrick’s Day madness–a retro glam band in a gorgeous space with a singer the Irish Voice named one of the “Most Influential Women of 2010.” Celebrate a week early, then cozy up with the paper and a movie on the 17th when the the streets will run green with beer and the subway is no place to be. Tickets, $60 per person, $100 per couple ($50/$90 for Green-Wood members) , include drinks and hor d’oeuvres; all proceeds benefit the Green-Wood Historic Fund.