They shall build the old wastes. (On the "waste" condition, not of Jerusalem only, but of the cities of Judith generally, see Isaiah 44:26; Isaiah 49:8, Isaiah 49:19; Isaiah 64:10, Isaiah 64:11, etc.) The first step in the recovery of Israel from the misery of the Captivity would be a return to Palestine, and a general restoration of the ruined towns.
It was a ruin of "many generations," having commenced, probably, with the invasion of Pharaoh-Necho in b.c. 608, and being continued till the edict of Cyrus.