The Boston Landmarks Orchestra is an all-star ensemble that presents a daring repertoire of both modern and classical compositions. As part of their commitment to accessibility, every concert the group presents is free. This year’s lineup ranges from a crowd-pleasing tribute to George Gershwin and John Williams (July 24) to an Arabian Nights program (Aug. 21). The Aug. 3 program includes the first-ever public performance of underrecognized Black 20th-century composer Julia Perry’s “Four Spirituals.” The Aug. 14 “Mozart & More” program will also be presented for free at Hibernian Hall in Nubian Square on Aug. 15 with two additional Boston neighborhood performances that week to be announced.