They're not name-checked as often as the Beach Boys or the Dead, but Chicago rank as one of the most popular American rock bands of all time. Beginning with their 1969 debut LP, Chicago amassed 5 consecutive No. 1 albums, 21 Top 10 singles, and 35 Top 40 singles, drawing fans with their free-flowing rock style, which took cues from jazz, R&B, blues, and more. This lavish six-disc set spans the band's impressive -- and ongoing -- career, from their beginnings as a septet called the Chicago Transit Authority dabbling in ambitious compositions like the four-movement "Ballet for a Girl in Buchannon" to purveyors of familiar songs like the driving classic rock nugget "25 or 6 to 4." The Box also highlights Chicago's reign as soft-rock stalwarts with hits such as "Saturday in the Park" and "Hard Habit to Break" before coming full circle with a splashy reading of Duke Ellington's "Caravan" and the 1999 collaboration with Lenny Kravitz, "The Only One." The set's first three discs span Chicago's achievements through the late '70s, setting familiar hits such as "Does Anybody Really Know What Time It Is?" and "Baby, What a Big Surprise" alongside more offbeat fare, such as the Cream-like dirge "South California Purples," the percussion-driven Latin instrumental "Mongonucleosis," and the lushly arranged "Brand New Love Affair -- Parts I & II," in which late guitarist Terry Kath comes off sounding like Ray Charles. Discs 4 and 5 track Chicago's move from disco-soaked tunes like "Street Player" to their collaborations with production Svengali David Foster on a string of smash ballads, from "You're the Inspiration" to the early-'90s Stone of Sisyphus album, which was rejected by Warner Bros. but is represented here by three previously unreleased tracks. The sixth disc, a bonus DVD, features live performances from a 1972 concert, along with a promotional film made for the release of Chicago 13. The icing on the cake, the set's deluxe booklet, collects detailed track notes, essays by Phil Gallo and A. Scott Galloway, and numerous archival photos, making The Box as appealing to casual fans as it is imperative for diehards.