Eight out of every ten New York City skyscrapers originated here, not to mention every bridge and tunnel linking New Jersey and Manhattan. Wartime product was even grander: 1,127 World War II-era ships, as well as every 16-inch gun and 40% of American artillery shells used during both global wars. Despite helping to forge the nation’s industrialization, the Bethlehem Steel Plant, once a symbol of the U.S.’s industrial might, has been silent for two decades now.

By the height of the U.S.’s industrial boom, Bethlehem Steel Corporation was the nation’s second-largest producer of steel and the plant in southside Bethlehem, Pennsylvania stretched for four-and-a-half miles along the shore of the Lehigh River. (Here is a link to the site on Google Maps.)

With the shuttering of the plant in 1995, some 1,800 acres of infrastructure once devoted to heavy industry stood vacant–an urban explorer’s wet dream, it seems. But not so fast. If ever there was a period you could roam through this long network of abandoned buildings, that time has passed, and the old Bethlehem Steel Plant now stands as a phoenix of sorts, a shining example of brownfield reuse.

Local officials didn’t simply throw up their hands in surrender to the world’s evolving economy (cheap foreign competition was one reason Bethlehem Steel eventually folded). They instead took advantage of changing economics and encouraged redevelopment of the Bethlehem Steel Plant, drawing people to new attractions at the old tract, which is why visitors can attend festivals and concerts presented by ArtsQuest, play a hand or two at Sands Bethlehem, and will soon be able to see the National Museum of Industrial History.

And, of course, for those who wish simply to wander the ruins of what our nation once was, that’s possible, too. Still remaining are brick facades, vine-choked walls and broken windows, behind which steelworkers once labored night and day to meet the demands of an industrializing world. It’s an intimate look at America’s Rust Belt, urban exploration that’s not only safe (fences clearly indicate where you should and shouldn’t be), but encouraged.

A good place to start is in the Bethlehem Visitor Center, one of the plant’s oldest buildings (dating to 1863) that sits in the shadow of an icon of this industrial core: the towering blast furnace that stands like a sentry guarding these honorable remains. I popped in and the attendant filled me in on the site’s transformation. The most dangerous structures, she told me, will be razed, or already have been, but many of the buildings that are still structurally sound will remain.

And those steel stacks still looming over this site? I asked her whether they’re considered too dangerous or unsightly, if they might become a casualty of the redevelopment. “No chance,” she told me. “Those will stay forever. They have a special place in the heart of this community.”