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
NEW 21000 Lego ARCHITECTURE Willis Tower Building Toy SEALED BOX RETIRED A 673419113274 | eBay
LEGO Architecture Ref.21000 - Willis Tower
Amazon.com: LEGO Architecture Willis Tower (21000) : Toys & Games
LEGO Architecture Willis Tower (21000) Excellent Condition Used | eBay