  We present dielectric measurements of the colossal dielectric constant
material CaCu3Ti4O12 extending up to 1.3 GHz also covering so far only rarely
investigated single crystalline samples. Special emphasis is put on the second
relaxation reported in several works on polycrystals, which we detect also in
single crystals. For polycrystalline samples we provide a recipe to achieve
values of the dielectric constant as high as in single crystals.
