I missed finding this area on each previous visit to Bethlehem Steel. I was always so concerned with climbing to the top of the coke battery that I neglected to search what was below.
Granted, there wasn't an obvious entrance and it didn't look particularly inviting. But, once you crawled inside, this wonderful tunnel revealed itself. The rather shaky (and deteriorating) metal grate floor wasn't too trustworthy, so I didn't move much more than a few feet from where I entered.
Had I made another return visit, I'd certainly return to this spot again. For now, it remains the probable inspiration for the Battlestar Galactica Viper launch tubes.