Large cavities (≈10-12.3 nm) of cubic (Fm-3m) mesoporous silica without intergrowth are synthesized in the presence of block copolymer templates. The entrance sizes of these cavities can be adjusted in the range of ≈4-9 nm as confirmed by nitrogen sorption studies and an examination of the negative gold replicas. The 3D open mesostructures facilitate the transportation of biomolecules (see picture), as well as the replication of a large-pore (9 nm) cubic mesoporous carbon.