Armstrong's Par & Grill was established by Robert Armstrong (opening date unknown) who graduated from herzing institute of technology. According to online reviews, the bar was well liked for its home-made recipes and low prices. From what I could piece together, the owner fell into financial trouble and the restaurant was sold off to the city (date unknown) where it now sits abandoned on Prudhomme Landing.
Armstrong's Par & Grill is a sports themed restaurant connected to the Prudhommes Inn through a small breezeway. Unfortunately I couldn't find much more information on this establishment as there is a chef with the last name "Prudhomme" and many restaurants named Armstrong's "Bar" and grill. Thus, making finding any information or history on the place very difficult.
The most recent information I could find on the restaurant is a 5-star review from April 17th 2012 so it must have closed sometime after that. During my visit, there were several broken windows and cracked doors but just as with the Prudhommes Inn someone seems very persistent in boarding up all the holes, denying any outside access. Be careful as this location is attached to an active subway restaurant.