foundation stone

The Foundation Stone (Hebrew: אבן השתייה, translit. Even haShetiya) or Rock (Arabic: صخرة translit. Sakhrah, Hebrew: סלע translit.: Sela) is the name of the rock at the heart of the Dome of the Rock in Jerusalem. It is also known as the Pierced Stone because it has a small hole on the southeastern corner that enters a cavern beneath the rock, known as the Well of Souls. It is the holiest site in Judaism (Midrash Tanhuma, chapter 10); Jewish tradition views it as the spiritual junction of Heaven and Earth. Jews traditionally face it while praying, in the belief that it was the location of the Holy of Holies in the Temple.

The cornerstone (or foundation stone) concept is derived from the first stone set in the construction of a masonry foundation, important since all other stones will be set in reference to this stone, thus determining the position of the entire structure.