Octaphenylnaphthalene (2) was synthesized by the addition of tetraphenylbenzyne to tetraphenylcyclopentadienone, and decaphenylanthracene (3) was synthesized by the addition of the same aryne to hexaphenylisobenzofuran followed by deoxygenation of the adduct. The structures of both compounds were determined by X-ray analysis. Compound 2 adopts a conformation of approximate C-i symmetry with a slightly undulating naphthalene nucleus, but compound 3 exhibits C-2 (and approximate D-2) symmetry with a 63 degrees twist of the central anthracene.