THE tombs of the second class are subterranean chambers approached by horizontal avenues hewn usually in a rocky hillside. In their construction, the workmen began at a given point in the slope and cut the dromos "in the form of a trench" straight into the hill, so that the bottom was horizontal while the vertical sides increased in height as the work advanced. At the inner end of the dromos -- in effect a vertical rock-facade -- a doorway would then be cut, and the chambers, usually square or oblong, hollowed out. The débris would be carried out through the dromos, of course, as the chamber, hewn in the solid rock, had no other exit. These simple rock excavations we shall, for convenience, call chamber tombs.
From them we must distinguish those "artificial subterranean chambers" in the form of a vault or beehive. Both have in common the dromos, but the construction of the tomb itself is notably different. Instead of a horizontal excavation proceeding from the dromos, a circular shaft is sunk vertically from the rock surface (just as in making a lime-kiln nowadays) to the level of the dromos and in due proximity to it. In this cavity the tholos is built up in circle upon circle of regular ashlar masonry, each course overlapping the one below it so as to form a