Büyükkaya

Seen from the Lower City, the rugged cliffs of Büyükkaya ( = Great Rock) are most impressive, rising precipitously some 100 m from the valley floor. A small settlement existed high up on the summit in the Chalcolithic, about 4000 years before the arrival of the Hittites. The Early Bronze Age Hatti lived there as well, and in their turn the Hittites erected a monumental structure on the summit of Büyükkaya, of which only foundation segments survive.
The true character of Büyükkaya is visible only from "the back"; approaching from Yozgat -or on your way to Yazılıkaya and back-you notice that the rise is actually a long high ridge enclosed by a fortification wall.
Originally, which is to say sometime in the 16th century BC, the fortifications ran only along the southeast, starting from the crossing in the gorge at Ambarlikaya. They were then continued to the north, over the high ridge of Büyükkaya and down, where they met the Northern City Wall (General Plan: No.38), which arched in a wide bow to rejoin the Lower City and the Postern Wall. Later, perhaps as late as the 13th century BC, another fortification wall was erected on the north side of Büyükkaya, which met the "Abschnittsmauer" (i.e. the fortress wall cutting through the Lower City) at the rock called Mihraplikaya. Thus the rise was transformed into an exceptionally well protected fortress.
In the 13th century BC Büyükkaya was used as a giant granary. The supplies for the city and country were stored here in rectangular cellars dug into the earth; the floors were paved. The largest of these storage bins, 11 of which have been so far discovered (there were doubtless more), measures 12 x 18 m and was certainly more than 2 m deep. This alone would indicate a capacity for at least 260 tons of grain.
Once these bins were filled with grain, they were decked with a thick layer of soil. Thus sealed from the air, the grain used up what remained of the oxygen and gave off carbon dioxide. The resulting atmosphere deterred any damage from pests; neither vermin-rats, mice and beetles-nor fungi could survive. It was ideal preservation, and could keep the grain for years at a time. This same principle of storage is used today in many countries of the third world; indeed it is still practiced in some parts of Turkey.

For details see: Forschungsbericht Büyükkaya-Grabung