There were about as many ideas for development on Chicago’s high-profile real estate at Wolf Point as there are Chicagoans. One you didn’t hear about during Alderman Brendan Reilly’s initial public meeting was The Clean Tower—a supertall that would return filtered wastewater to the Chicago River beneath its slanted profile. The Clean Tower wasn’t actually on the table for Wolf Point, but it does occupy real estate on the Chicago Architecture Foundation’s model of downtown. That’s because it’s part of Unseen City: Designs for a Future Chicago, an exhibition of imaginative projects from Illinois Institute of Technology's “Hi-Rise, Lo-Carb” studio. Hi-Rise, Lo-Carb—led by Antony Wood of the Council on Tall Buildings and Urban Habitat (CTBUH), and Adrian Smith + Gordon Gill Architecture—begat six projects, including a vertical neighborhood in the Loop complete with “streets in the sky,” and a "Post [Waste] Office" that envisions the vacant Old Chicago Main Post Office as a sustainable waste management center with a rooftop arboretum. This is the first time the Chicago Architecture Foundation has opened up its model of downtown for use as an exhibit space, and Unseen City is an excellent start. The model’s urban context legitimizes the ambitions of these inventive projects — placed alongside existing institutions in the Loop, they inspire progressive thoughts. Glimpse the unseen city in the lobby of the Santa Fe building, 224 S. Michigan Ave., through November 4.