There are two particulars relating to the Propylæa, and to the works about them, which I have not yet mentioned. We see in various places remains of piers and walls of a very ancient masonry, of limestone, and not of marble; apparently earlier than the time of Pericles; there is such a fragment under the north-west angle of the northern wing of the Propylæa, whose lines not exactly corresponding with those of the work above, prove that they did not form part of that design. The base of the pier which contains the inscription to Agrippa, is of a grayish slaty marble, not used in the upper parts, and this perhaps may also be more ancient than the pier it supports. The other circumstance is, that the work has not been completely finished, and that we are thereby enabled to trace the mode of execution. It appears that the Athenians worked the marble to an even, but not a very smooth face, with a toothed chisel, before they placed the blocks in the work, and that they afterwards went over the whole exposed surface, and finished it to the greatest smoothness and nicety, but without polish, taking off in this operation about one fifth of an inch; and this has been the practice on the horizontal, as well as on the upright surfaces, for the columns of the Propylæa are sunk in to about that depth below the general level. The place intended for their reception was sunk before the lower cylinders were placed, and lest any inconvenience should arise from the wet remaining there, before the building was completed, a small channel has been cut from the recess to carry off the water. In the steps, the adjoining faces are carefully finished at the internal angles, but both are left rough at the external angles, by which means the accidents and wear which take place during the execution of the work, would rarely be of any consequence.