What type of garage ceiling is this?

Home built in 1965. There is rebar inside the cemented areas, but they look like some type of concrete blocks. Just curious, first time seeing this.

What was above this ceiling? It does look like block, but I can not tell

It was a builtup/tarred roof under the rooftop porch

I’ve seen that type of flooring used at the Boldt castle in NY 1000 Islands during a tour. The castle was built in 1900. Its a concrete block flooring system.

Its a formed and poured slab/ ceiling. You install supports, install decking, tie rebar in a certain pattern, place concrete, finish the surface, remove the forms and supports, install roofing, go home.