+PREHISTORIC MONUMENTS.+[7] Authentic Greek history begins with the first Olympiad, 776 B.C. The earliest monuments of that historic architecture which developed into the masterpieces of the Periclean and Alexandrian ages, date from the middle of the following century. But there are a number of older buildings, belonging presumably to the so-called Heroic Age, which, though seemingly unconnected with the later historic development of Greek architecture, are still worthy of note. They are the work of a people somewhat advanced in civilization, probably the Pelasgi, who preceded the Dorians on Greek soil, and consist mainly of fortifications, walls, gates, and tombs, the most important of which are at +Mycenæ+ and +Tiryns+. At the latter place is a well-defined acropolis, with massive walls in which are passages covered by stones successively overhanging or corbelled until they meet. The masonry is of huge stones piled without cement. At Mycenæ the city wall is pierced by the remarkable +Lion Gate+ (Fig. 22), consisting of two jambs and a huge lintel, over which the weight is relieved by a triangular opening. This is filled with a sculptured group, now much defaced, representing two rampant lions flanking a singular column which tapers downward. This symbolic group has relations with Hittite and Phrygian sculptures, and with the symbolism of the worship of Rhea Cybele. The masonry of the wall is carefully dressed but not regularly coursed. Other primitive walls and gates showing openings and embryonic arches of various forms, are found widely scattered, at Samos and Delos, at Phigaleia, Thoricus, Argos and many other points. The very earliest are hardly more than random piles of rough stone. Those which may fairly claim notice for their artistic masonry are of a later date and of two kinds: the coursed, and the polygonal or Cyclopean, so called from the tradition that they were built by the Cyclopes. These Cyclopean walls were composed of large, irregular polygonal blocks carefully fitted together and dressed to a fairly smooth face (Fig. 23). Both kinds were used contemporaneously, though in the course of time the regular coursed masonry finally superseded the polygonal. [Footnote 7: For enlargement on this topic see Appendix A.] [Illustration: FIG. 23.--POLYGONAL MASONRY.]