Chicago History Time 4D Cityscape Puzzle: This puzzle recreates "The Windy City's" famous skyline, not only in three dimensions using scale-model buildings, but also along the fourth dimension time—spanning 100 years of its architectural history. The puzzle includes 127 building replicas that depict the city as it appeared as far back as 1873 through to 2015, including iconic structures such as the Willis Tower, John Hancock, Navy Pier, and the Chicago Spire. Each building replica fits into pre-cut holes in a traditional 2D jigsaw puzzle composed of 831 pieces that form the city's street layout and islands. The product includes a Time Poster that directs you through time as you rebuild Chicago's skyline history. The finished puzzle measures 19" L x 19" W x 5" H. 950 pieces. For ages 8 and up.