A hulking building that looks like an Italian Renaissance fortress, Chicago’s main public library is the largest in the world, and even has its own El stop. Named for the city’s first and only African-American mayor, who died of a heart attack in 1987 at the beginning of his second term in office, the building fills an entire city block at State Street and Congress Parkway. The interior design has been criticized for feeling cold and impersonal (you have to go up a few floors before you even see any books), but the stunning, 52-foot glass-domed Winter Garden on the top floor, with its terrazzo and marble floors and giant glass dome, is worth a visit. On the second floor is another treasure: the vast Thomas Hughes Children’s Library, which makes an excellent resting spot for families traveling with kids. The library also offers an interesting array of events and art exhibitions that are worth checking out. A 385-seat auditorium is the setting for a unique mix of dance and music performances, author talks, and children’s programs, and visitors can stop by the third-floor Computer Commons, which has about 75 terminals available for public use, to check email. The high-tech Maker Lab offers free workshops. Allow a half hour.