In such a survey it is usual to give a place to early walls of fortification, although these, to be sure, were almost purely utilitarian in their character.  The classic example of these constructions is the citadel wall of Tiryns in Argolis.  Fig. 22 shows a portion of this fortification on the east side, with the principal approach.  Huge blocks of roughly dressed limestone—­some of those in the lower courses estimated to weigh thirteen or fourteen tons apiece—­are piled one upon another, the interstices having been filled with clay and smaller stones.  This wall is of varying thickness, averaging at the bottom about twenty-five feet.  At two places, viz., at the south end and on the east side near the southeast corner, the thickness is increased, in order to give room in the wall for a row of store chambers with communicating gallery.  Fig. 23 shows one of these galleries in its present condition.  It will be seen that the roof has been formed by pushing the successive courses of stones further and further inward from both sides until they meet.  The result is in form a vault, but the principle of the arch is not there, inasmuch as the stones are not jointed radially, but lie on approximately horizontal beds.  Such a construction is sometimes called a “corbelled” arch or vault.

Similar walls to those of Tiryns are found in many places, though nowhere else are the blocks of such gigantic size.  The Greeks of the historical period Viewed these imposing structures with as much astonishment as do we, and attributed them (of at least those in Argohs) to the Cyclopes, a mythical folk, conceived in this connection as masons of superhuman strength.  Hence the adjective Cyclopian or Cyclopean, whose meaning varies unfortunately in modern usage, but which is best restricted to walls of the Tirynthian type; that is to say, walls built of large blocks not accurately fitted together, the interstices being filled with small stones.  This style of masonry seems to be always of early date

Portions of the citadel wall of Mycenae are Cyclopean.  Other portions, quite probably of later date, show a very different character (Fig. 24).  Here the blocks on the outer surface of the wall, though irregular in shape. are fitted together with close joints.  This style of masonry is called polygonal and is to be carefully distinguished from Cyclopean, as above defined.  Finally, still other portions of this same Mycenaean wall show on the outside a near approach to what is called ashlar masonry, in which the blocks are rectangular and laid in even horizontal courses.  This is the case near the Lion Gate, the principal entrance to the citadel. (Fig. 25)