History of the Peloponnesian War

The same summer the Syracusans learned that the Athenians had been joined by their cavalry, and were on the point of marching against them; and seeing that without becoming masters of Epipolae, a precipitous spot situated exactly over the town, the Athenians could not, even if victorious in battle, easily invest them, they determined to guard its approaches, in order that the enemy might not ascend unobserved by this, the sole way by which ascent was possible,

as the remainder is lofty ground, and falls right down to the city, and can all be seen from inside; and as it lies above the rest the place is called by the Syracusans Epipolae or Overtown.