During construction work on the eastern slope of Mt. Scopus, a bulldozer broke through the ceiling of a large cave. It became immediately apparent to archeologists that the cave was man-made and had served as a quarry and workshop for the production of stone vessels, of a type well known from the late Second Temple period in Jerusalem.
This period was characterized by increased observance of halachic (of the halacha, Jewish Law) purity laws among the Jews. According to halacha, stone vessels, unlike pottery vessels, do not become ritually impure. Thus stone vessels were widely used as tableware, and for the storage of water and food, and many have been uncovered in archeological excavations.
The site consists of two separate underground cave complexes with a total area of about 5,000 sq.m., cut into a Senonian limestone layer. This rock formation was chosen for its softness, suitable for the manufacture of such vessels. The quarrying of rectangular stone blocks of about 1.5 x 0.7 m. left cutting grooves in the walls, floors and ceilings of the cave. After cutting around the blocks, they were detached from the bedrock by hammer-blows on metal wedges inserted behind them. From these blocks the stone vessels were manufactured in the quarry, some on lathes, some by hand.
Quantities of wasters of stone vessels discarded during the various production stages, and large numbers of cylindrical stone cores of different sizes (removed from the vessels during lathe-turning) attest to the manufacture of tens of thousands of items. Activity in the caves took place in the 1st century CE, until the destruction of Jerusalem by the Romans in the year 70 CE. Whole, undamaged vessels were not found; they were apparently delivered to the markets of Jerusalem and its environs.
Sources: Israeli Foreign Ministry