Yes, Rosa’s Cantina is (and was) a real place, although it didn’t exist in the Old West sense described in the famous song.
When Robbins passed through in 1958 the (then-new) joint was closed for the day but the location inspired the song. Here is the view out the front door of Rosa’s:
Reminds one of the lines:
"And at last here Im on the hill overlooking El Paso; I can see Rosa's cantina below. My love is strong and it pushes me onward. Down off the hill to Feleena I go."
The cantina is a rock building with an adobe-like stucco outer layer, eroded in places. There is an abundance of rock in the area so that is the most common building material in older structures.
[side view; front door is where the wrought iron gate is, partially obscured by the black signpost. The aforementioned hills are to the right]
It’s basically a small honkey-tonk with a cafe area. It’s quite loud:
Remember that hearing damage starts at 85dB, and Rosa’s hit 84.3dB in the screenshot below.
It’s not that I’m a “get off my lawn” old guy, it’s that I have always been sensitive to loud noises. I carry earplugs everywhere.
As I paid my waitress, I asked if I could leave the establishment by running out the back door (a dark, heavy wooden item), _a la _
"Out through the back door of Rosa's I ran Out where the horses were tied I caught a good one, it looked like it could run Up on its back, and away I did ride"
She smiled and said the door is not longer an exit because HVAC equipment now abuts the back wall.
The food was edible but the lively bar area is the real draw. Folks having friendly, good-natured fun, which is how El Paso does things.