We demonstrate a new method that makes use of colloidal silica templates to fabricate porous three-dimensional architectures of carbon nanotubes (CNTs). CNTs were grown on monolayered and multilayered structures of colloidal silica using chemical vapor deposition. Porous CNT membranes and three-dimensional carbon nanotube foams were obtained by treating these silica-CNTs structures with HF. The membranes and foams of CNT so obtained were chemically and mechanically stable and were characterized by using scanning electron microscopy and energy dispersive spectroscopy.