The railing on the right belongs to the bicycle path bridge, built in the early 1980s, the small stone bridge in the of middle of the photo is Hermit's Lane, built in 1794, and the big fellow overarching it all is the Henry Avenue Bridge, completed in 1931. Gotta love those layers of history.
If you've ever seen the John Travolta film Blow Out, these bridges might look familiar to you. Some, or all of them, appear near the beginning. I haven't seen the film in years, nor do I intend to see it again. I remember it being filled with gratuitous violence, bordering on misogyny.
But hey, the bridges are still cool.