The Indigo Girls, the Atlanta-based duo whose eponymous 1989 major-label debut snagged a Grammy Award for Best Contemporary Folk Recording, will be in concert Monday, March 17, at Track 29, 1400 Market St. Doors open at 7 p.m., and the show starts at 8 p.m., with Hannah Thomas opening. The Indigo Girls -- Amy Ray, left, and Emily Saliers -- have since sold in excess of 12 million records and earned six more Grammy nominations. Tickets are $30 in advance, $35 day of show, which is open to ages 18 and older (photo ID required). For tickets, call 423-521-2929 or visit www.track29.co.