Open only to pedestrians and cyclists these days, this mile-long span over the Mississippi River opened in 1929 and was a vital link in Route 66. It has a 30-degree angled bend (the cause of many a crash, hence the ban on cars). Closed to vehicles since 1968, the bridge provides links to various regional trails. It's closed on the Missouri side to pedestrians who arrive by car due to vandalism.
On the Illinois side, before driving into Missouri, detour off I-270 at exit 3. Follow Hwy 3 (aka Lewis and Clark Blvd) south, turn right at the first stoplight and drive west to the bridge. Hide your valuables and lock your car before you go exploring.