Bridges are one of the few architectural endeavors that are both functional and symbolic. Spans like the Golden Gate, the Brooklyn Bridge, and the Tower Bridge of London capture the popular imagination, while still serving an essential purpose. During the middle ages, inhabited bridges became popular as a means of connecting communities. Today, architects are re-imaging the inhabited bridge as a way to make the fullest, most eco-friendly use of a functional space. These pictures reveal some classic inspiration for inhabited bridges as well as some amazing 21st century takes on an old concept.