As a Chicago resident and Architecture fan, I love these three... as a fan of build techniques, man - 21000 and 21001 are some of the worst sets I've put together. : r/lego
LEGO Architecture Both Sears & Willis Tower In Bags (21000) RARE RETIRED SET | eBay
Lego Architecture Willis Tower 21000 3D model | CGTrader
Amazon.com: Sears Tower Chicago Illinois USA LEGO 21000 ORIGINAL : Toys & Games