While he was still working for Louis Sullivan, Frank Lloyd Wright (who was 19 at the time) designed the 11-room Charnley-Persky House, which sparked a new era in architectural design. Why? Because it did away with Victorian gaudiness in favor of plain, abstract forms that went on to become the modern style. It was completed in 1892 and now houses the Society of Architectural Historians.

　　Guided one-hour tours are offered on Wednesday; they're free and first-come, first-served, up to 15 people. Tickets for the Saturday tours can be purchased from the website.