There where more than People dancing at the old Evergreen Hotel in Ross twp.

Its long gone now just an empty lot the state owns in anticipation of  some day enlarging the intersection  of Babcock blvd and Evergreen Road   where the old  historic wooden Evergreen Hotel sat but sadly in its last days it suffered a fire and a decline which saw prostitution busts. But in its heyday it was the place to dine eat and dance and stay overnight.Every time I passed it despite the fact it was falling apart it was a real gem.

http://www.post-gazette.com/local/north/2009/11/05/Evergreen-Hotel-in-Ross-to-be-sold-by-state/stories/200911050332

 But beside the nasty reputation it got over the years there where rumors of other guests as well the unseen type.
Guests have been knocked down stairs and locked in restrooms  had hair pulled and employees harassed. 

https://sites.google.com/site/hauntsandhistory/threerivershaunsandhistory2

Excerpt from web site 

 EVERGREEN HOTEL (Millvale, Allegheny County) The Evergreen has a mottled history, going from a hotel built in 1874 to a bar to a strip club. Poltergeist activity has allegedly occurred for years there – slamming doors, breaking dishes, lights going on and off, customers being locked in the bathrooms, help being locked in the cellar, and cold spots upstairs (although rowdy clientèle could be thrown into the mix of suspected causes, too). The ghostly guests should be pleased that the Babcock Boulevard Evergreen has become JezeBelle's Dance Club & Showbar, not a pizza shop as reported. The show must go on.  EDIT - The show has stopped.  The state seized the building because of alleged drug activity, and it has been condemned

Not a friendly ghost at all but a poltergeist. I know several people over the years who told story's about the place being haunted. 
This is but one of several haunted locations in the North hills which seems to have more than its share of scary places.