Complex sentence: Although referred to as a dome it is not strictly one as it is not self-supporting, but is in fact a giant Big Top, the canopy being supported by a dome-shaped cable network, from twelve king posts.
Split into simpler sentences: Although referred to as a dome it is not strictly one as it is not self-supporting, but is in fact a giant Big Top. The canopy being supported by a dome-shaped cable network, from twelve king posts.