Is this a sewer cover or an old septic cover?

Yesterday’s inspection, property built 1950, public water and sewer. At rear of property was a concrete cover dated 1949, located at rear of home (also covers present at both properties at left and right sides)
I think is a public sewer cover, not sure. I have seen some septic systems in area.

Carlos Orellana
Houston Texas.

I have never seen a public sewer cover in a back yard. Makes no sense. If it was an old septic tank/cistern system, it should have been “abandoned” when the home went on the public system, therefore there would be no need for the concrete cover. Locally, when they abandon septic tanks, the tank is pumped out, the bottom is punched out and filled with new soil. I found a home a year or so ago that had a septic tank in the back yard with only a sheet of old 1/2 inch plywood covering the entire tank. Buyer almost walked across it before I stopped him. He would have gone swimming and I would not have jumped in the save him. Careful where you walk in back yards.