These are simply hollow concrete domes domes that are primarily used for storage, but can also be used as accommodations. Designed in early 70's, construction was quick and cheap. It will have a rebar skeleton and concrete would be poured on top. A giant balloon would act as scaffolding, which would deflated and taken away once the concrete had cured. I am not too sure about its historical significance though. As a child, saw plenty of these being built back home for grain storage. Out of trend nowadays as shipping containers are much convenient storage option. Hope this helps.