As they chisel away the rock, they've got to be careful not to damage what archaeologists have been looking for more than two centuries. Historians say here is where rebels took back Jerusalem from the Greeks, a victory marked in the holiday of Hanukkah.
"Small finds related to this discovery are mainly coins but other artefacts… And we know that the dating of this fortification system precisely falls within the presence of Hellenistic presence here in general and the civilisation timed here in the beginning of the 2nd century BC."
The fortress is estimated to be 250 metres long and 60 metres wide.
The debate over the location of the 2,000-year-old Accra has seen many claim it stood in Jerusalem's Old City at spots like the Christian Church of the Holy Sepulchre near where to Jewish temples also lay. But the remains unearthed this week are outside the walls overlooking an area known as the City of David.