The structure of highly polymerized three-dimensional (3D) fullerite C₆₀ was studied by energy dispersive x-ray diffraction up to a pressure of 11 GPa. It is shown that this phase combines the features of an amorphous sp²–sp³ covalent network and a crystallographically ordered phase with a long-range translational order associated with the modulation of the atomic density inherited from initial C₆₀ molecules. Crystal reflections can be described in the framework of the fcc structure with an initial normal-pressure parameter of 11.718 Å, although this is probably the effect of averaging x-ray scattering. The bulk modulus of highly polymerized 3D C₆₀, 280 GPa, determined from the pressure-induced change in the lattice parameter, is in agreement with the measured density and crystallographic density, as well as with the first coordination number Z=3.6, determined from the radial distribution function according to the theoretical calculations.  The value of Z indicates that ~60% of carbon atoms are in sp³ hybridized states and a high degree of polymerization is achieved due to [3+3] cycloaddition. Correlation between the density and bulk modulus is discussed for a wide set of carbon phases.