I have played this original
Chicago Transit Authority album many times since I purchased it back in 1969. And, it has not worn out, yet.
It must be "Gold-Plated"

I love Jazz and I love Rock.....and, Chicago has always provided a good blend of both these music styles.
From the
Beginnings 
my favorite song of theirs is....
Does Anybody Really Know What Time It Is ?
Every time I hear it, I have "flashbacks" to some very fond times in my youth.
Saw them live in 1973 in Westbury (NY), and in 1993 (Valley Forge Music Fair).
TED Z
.