The interior of a macroverse is indescribable. It appears to be made of repeating fractal structures composed of stars, galaxies, and even entire Superclusters. These objects swirl around each other in vortices trillions or quadrillions of lightyears wide, which in turn combine to form huge pillars and sheets of vortices. The pillars and sheets stack on top of each other and swirl around in larger and larger groups in much the same way that turtlies do; four-, five-, and six-dimensional polytopes, impossible Escher-like bridges between spheres of light, and objects so vast that even deities could not comprehend their true size.
The most advanced of civilizations, which have practically ascended to godhood or even past this, use macroverses for large-scale storage of immense battlefleets, fortresses, or other tech that simply needs a place to stay before it is deployed.