Going through the south loop so many buildings have been torn down or have changed. Pre-1999 there was a grill on the 8th floor of a old office building. I ate there a few times and was told it was there for a long time. The place had a name but didn't advertise it. People in the area knew about it and was open from early morning till 2:00 PM. As you walked in the building you took a old elevator up to the 8th floor. When exiting the elevator it was like a office hallway. A door to the left of the elevator was the grill. The grill had a counter with about 12 stools. 4 tables were against the window looking over the street. They had one waitress and one cook. This place was in a building on the west side of the street. The building was on S. Michigan Ave. or S. Wabash around 11th Street.

By your description it sounds like you could be thinking of what is now known as Heaven on Seven, located at 111 S. Wabash 7th floor. It's gone by this name for at least 20 years, if not longer, and is known for its Cajun Creole menu. However, before it went by this name, it was a traditional diner whose name escapes me. Back in the day there were several upper level diners or cafeteria style restaurants in the Loop. Most were located in older office buildings. Later, many of these diners relocated to the main floor or basements as those locations made it easier to gain pedestrian traffic. The Chicago Board of Trade still has a popular basement cafeteria and I think there may yet be one in the LaSalle Bank building. The basement cafeteria in the Bank of America building (old Continental Bank) closed a couple of years ago. I worked in the Loop for 40 years and up to about 20/25 years ago there wasn't nearly as many franchise fast food joints as there are now. Times change.

@ambrosemario, Thank you for your help. My mistake on the location. This building was south of Roosevelt about 3 blocks. It was a dive but very good and hearty food. It was lunch counter type place where most people working in the area probably didn't know existed. But you would get locals, people working very close by, police etc. The place looked like it was never remodeled ever since it opened. They had a small restroom in a storage room. You can smell the burgers frying on the grill as you went up the elevator. I didn't know the Bank of America building cafeteria closed. It was always busy back in the 1990's. Thanks again

The place just came back to me after wondering what it was called. The name was the Paris Snack Shop on the 7th floor of 1104 South Wabash Avenue which I think was the past Warshawsky building. Thank you