Visions of the future have long captivated audiences—science-fiction fans, designers, and architects alike. A new exhibition organized by the AIA San Francisco and the Center for Architecture + Design for the upcoming Architecture in the City festival (September 1–30) explores a hyperlocal look at various "futures." Unbuilt San Francisco is divided into two parts: In "Dreams Deferred" spy conceptual proposals that will never be built or early iterations of some of the city's most beloved buildings. "On the Boards" presents projects that will be realized in the future, such as the Treasure Island master plan to be completed in 2020. The exhibition is on view now through November. A sampling of the works is in the following slideshow.For more conceptual experimental and visionary architecture from the past, visit our slideshow on Never Built: Los Angeles.