From 400 feet in the air, the nation’s second-longest pedestrian bridge (not to quibble over the details, but the present title-holder was originally built as a highway, which does seem kiiiinda like cheating) seems much smaller than it is. It’s tough to see the 24-plus million tons of concrete, the three million pounds of steel, the barge tows that pass so lithely through the Murray Lock and Dam (each of them a big, honking thing capable of hauling the equivalent of 870 big rigs, or 22,500 tons, according to the Corps of Engineers). And of course, you can’t really see the estimated 8.9 million people who’ve walked, run or ridden across the 4,226-foot span since it opened 10 years ago this month. What you can see? Whelp, it’s a fine dam bridge. No matter how you look at it.