This map is a composite of three maps distributed during Gaslight Square’s existence, supplemented by listings in available St. Louis City Directories. The longer of the two blocks was the 4200 block of Olive which is illustrated. Those businesses on Boyle are not illustrated. I have attempted to show the businesses that occupied each location in proper sequence, but I’ve had to guess in numerous instances. There are undoubtedly errors and omissions. (Click on image to enlarge.)
It's great to hear from readers and I take time to answer queries. I can't always find what you are looking for, but I do appreciate getting thank yous no matter what the outcome.
Restaurant-ing through history 
I saw it. The name was The Crystal Palace, not Opera House. Thank you for help and Marty Bronson sang there a lot.
Name the restaurant having staff sing show tunes
There was a lot of singing in Gaslight Square, mostly folk. The best known place with a singing staff was Marty’s, a restaurant owned by TV personality Marty Bronson. It was said that at Marty’s “singing could break out anywhere in the room.” But there were also singing servers at Bustle & Bowes and the chain place Your Father’s Mustache, probably others too.
Where on Chippewa or Watson was Parente’s restaurant located?
Parente’s Italian Village was located at 6600 Chippewa, at Watson.