Every year, Chicago's skyline gets a few new towers, prompting the Chicago Architecture Foundation to update its famous model of the city located at its Michigan Avenue HQ. As a permanent exhibition, the CAF's model grows along with downtown Chicago. And similarly, buildings that have been recently demolished (Prentice Women's Hospital) or projects that have fizzled out (Chicago Spire) are removed. This year, the CAF has added 16 new buildings and structures to its Chicago model. However, adding new buildings to the miniature city can be a precarious task.