Four stone courses of the eastern spring of the arch, consisting of a row of impost blocks and three layers of voussoirs, have survived to modern times. This remnant was first identified in 1838 by Biblical scholar Edward Robinson and now bears his name. At that time, prior to any excavations, remains of the arch were at ground level. The ancient street level lay far underground, buried by debris from destruction of structures on the Temple Mount and later fill dumped into the Tyropoeon Valley over the centuries. Robinson believed he had identified the eastern edge of a bridge that linked the Temple Compound with the Upper City which lay on the ridge to the west.