The mound at Göbekli Tepe was not unknown before the modern excavations.

Local people had always known the hill was there.

Survey archaeologists had visited and recorded it.

The site appeared in surveys conducted by the University of Chicago and the University of Istanbul in the 1960s, and it was assessed at that time as a likely medieval or Byzantine site — the surface stones, exposed in the grass and scrub, seemed relatively unremarkable, and the T-shaped tops of some pillars were interpreted as grave markers of the kind associated with medieval Islamic burials.

The assessment was not unreasonable given what was visible; it was simply wrong.