Considering that Sardis was perched on top of a virtually impregnable 1500 ft. high plateau, what means did the Sardinians use to commute from the top of the plateau to the bottom with somewhat ease?

Three sides of the palteau were vertical, and inpregnable. The South side of the plateau had a connection into the adjacent hill range, affording somewhat of a "ramp" for entry and exit, if my understanding of this is right. It was not sufficient enough for conquering armies to scale, though, because it would have meant sudden disaster to them. Their line of defense would have been extremely minimal.

When Sardis was beseiged by Persian King Cyrus, it was done so after a soldier discovered a crevice in the plateau itself, allowing the Persian army to scale the plateau and overtake the city.

Any one have any information on the standard fare of entry and exit to the top of that plateau?