The Parthenon is unusual for its mass of Doric refinements…Though these modifications to the horizontal and vertical are miniscule, there are nevertheless no true verticals or horizontals in the building, and hence no right angles. At the same time, these refinements impart a sense of mobility to `straight’ lines and avoid a boxlike appearance. Dignity of form was thus enhanced by dynamism of forms. The demands on the masons were enormous. All blocks, whether curving or not, had to fit flush; yet everywhere block fits meticulously with block, and only on one or two metopes does the carving betray signs of uncertainty or haste. Precisely proportioned, marvelously constructed without mortar or concrete, held together by iron clamps coated with lead to withstand corrosion, this magnificent structure haunts us today with its astonishing blend of technical know-how and grandeur. (253).