Boy bands come and go with tedious regularity, but the Vienna Boys' Choir maintain its 500 year history of satisfying fans worldwide. With approximately 100 sailor-suited choristers between the ages of ten and fourteen divided into four touring groups, the ranks are constantly changing and remain forever young. Tonight the group performs a special one-night-only Holiday Concert at the Cathedral Basilica of Saint Louis (4431 Lindell Boulevard; 314-533-7662 or www.cathedralconcerts.org ). Doors open at 7:30 p.m. and the show begins at 8 p.m., but arrive early to catch the opening act, a special performance by the St. Louis Boys' Choir. Tickets are $24 to $34, and not surprisingly, they're selling quickly.