Back around 1980, local TV would broadcast a regular program from Europe (France?) showing circus shows. This was when circuses with animals were still in vogue.
In one of these shows, the ring was covered in a loose substance (sand? sawdust?) for some act with elephants. The next act involved ice skating. So the entire floor of the ring dropped down to a lower level, and then rotated out of the way, and an ice rink rotated into place and rose up to ring level. During the transition, we could see that the brightly-lit basement level had multiple surfaces like this that could rotate around a central hub. The commentator was describing the high-tech swap-out as if it were an act in itself.
Does anyone know what venue this could have been? My recollection is that the surfaces were round, which would mean that this arena was only used for circus shows.