The haunted J&L Mill shop 2# on Pittsburgh's South Side no steel worker ever went back there by them selves unless they where looking for trouble.

I will never forget the one afternoon  in late 60's my mom and brothers and I went to pick up my dad from the mill and he was over an hour late getting out the mill gate . When he did finally come out to the van he had a very worried look on his face one of the workers he knew was missing in the Jones & Laughlin Massive  mill Complex he never checked out and my dad spent time looking for him.

 The worker would be found by a rescue crew later that evening  he had fallen and broke his leg and could not get help getting out  and his banging brought the crew to him but not with out its harrowing moments because he had fallen back in the old Mill shop 1 # and  2 #  area which was haunted by 40 dead steel workers souls who perished  after falling into a vat of steel  or other accident and noises he made trying to get attention caused just that much more tension going back to explore and find him. There was a bronze marker to all those who died in the mill on end of the old shop 2#  that was visible to public but I  do not know what happened to it after they tore down the old mill in 80's

http://www.popularpittsburgh.com/pittsburgh-trivia/spirits-of-the-steel-mills.aspx

My dad will tell you story's of when he had to go back into the old Shop 1# and  2# one time looking for possible parts to use to repair an old crane. 

he heard the wind blowing and banging and flapping of steel siding like there was a storm outside yet it was a perfectly calm summer day.

Old shop 1# and 2# in South side - thank you John Cross for photo image. 

Now how all this haunting started I have heard several stories
Including after a worker fell into vat and vaporized they would pour off a small amount and let it cool an give it to the family as a memorial and the tainted steel was then pored in a hole at the plant and discarded
and when renovations at the plant disturbed these old tainted pour offs which had workers who fell into them that's when the haunting's started.
The above article link also mentions Slag Pile Annie and I have never heard that story and know plenty of old steel workers who worked the south side works including several uncles none of them mentioned it  so this story appears to be just made up. Women did work the mill during WWII but never heard of any dying and they never would have been allowed do do any extremely dangerous jobs around the furnaces.
However one of my dads friends tells the time a worker was killed in the slag pits when water jet was turned on at wrong time . They used the jet on hot slag which granulated it to make it easier to handle and sell for use in driveways.

The mill has been replaced by a shopping complex and cinema and I have not heard of any further haunting's where the theater now sits on the old mill site.
So its either a bunch of old retired steel workers like my dad telling tales or there was something to it.
Of course now that the mill is long gone we will never be able to do further investigation of it.