The auditorium, or the portion of the theatre containing the seats for the spectators, was called the ‘cavea’ in Latin; but there was no technical name for it in Greek. In almost all Greek theatres it was built upon the side of a hill, so that the natural slope of the ground might serve as a foundation for the tiers of seats. At Athens, as we have seen, the rising ground at the foot of the Acropolis was utilized for this purpose, and supported the central part of the building. It was only at the two wings, on the east and west, that artificial substructures were necessary, in order to bring the back seats up to the proper height. The walls by which the auditorium was bounded on the outside have been preserved to a certain extent, and suffice to mark clearly the original shape of the building. On the western side of the theatre, from _a_ to _b_ in the plan (Fig. 3)[334], where a strong support was required for the embankment, a device was adopted which is still commonly employed at the present day. If a single wall had been erected, it must have been of enormous width. As a substitute two narrow walls were built in parallel lines, with cross-walls at intervals, and the intervening space was filled up with earth. Thus the same result was obtained at a less expense. Along the north-western curve of the theatre, between _b_ and _c_, a single wall proved sufficient, owing to the diminishing size of the embankment. At the point _c_ the rock of the Acropolis abutted upon the theatre, and was hollowed out into a regular curve. This is without doubt the portion of the theatre referred to by the ancients as Katatome, or ‘the Cutting’.[335] In the rock at this place is a natural grotto enlarged by artificial means, and 34 ft. long by 20 ft. broad. Here Thrasyllus erected an elaborate monument to commemorate his victory with a chorus of men in 319 B.C. In front of the grotto stood three columns supporting an entablature, and surmounted by a statue of Dionysus. On the architrave was an inscription recording the victory of Thrasyllus. Inside the grotto were statues of Apollo and Artemis destroying the children of Niobe. In modern times the grotto has been converted into a chapel of Our Lady. The columns and entablature were in excellent preservation when Stuart visited Athens, but they were shattered by a mine during the Greek revolution. Above the grotto are two columns, which were erected to commemorate victories with dithyrambic choruses. On the capitals can still be seen the holes made to receive the legs of the tripods.[336] After the Katatome the eastern boundary wall, from _f_ to _g_, is very peculiar in shape. But the reason of the irregularity has not yet been explained, owing to the scantiness of the remains in this part of the theatre. The two wings of the auditorium are terminated on the south by the walls marked _a-a_ and _g-g_. These walls are of unequal length, the eastern wall being about 111 ft., the western only 88 ft. They are not in