The East Plant and the damage it has wrought are famously described in Bill Bryson's book A Walk in the Woods[0]. It's still standing just north of the ridge the Appalachian Trail passes by on.
When I thru-hiked in 2010, vegetation was starting to take hold on the ridge and the slope leading town to the plant, but it was still pretty barren. The experience following that ridge is unique and unlike anything else on the entirety of the trail. Even if you walked that stretch without any knowledge of what had happened, it would be pretty clear that something had.
Bryson, I think rightly, takes a nuanced view of the site. It's easy to condemn the destruction and deforestation today, but most of us have benefited from the widespread use of zinc.
I wish I had popped into Palmerton to see the plant from the road instead of just from the ridge; I hiked through Lehigh Gap without hitting town, and I kind of regret it.
If you find yourself in the area and are inclined to take a hike to see the site from above, you should know that the hike up out of Lehigh Gap is both steep and completely unshaded. As long as you're in the area, it might also be of interest to know that Centralia isn't far away[1].
[0] And if you were turned off from ever picking it up by seeing the movie, I don't blame you. I assure you the book is better in every way.
