Tortoise is premiering new music this Thursday 7/29 at Millennium Park in Chicago – a commission by our hometown, with extra-special guests Nicole Mitchell – flute, Edward Wilkerson Jr. – sax and clarinets, Greg Ward – alto sax, Fred Lonberg-Holm – cello/electronics, and Jim Baker – piano/ARP 2600. 6:30 p.m. rain or shine, free admission.