He dwelleth in desolate cities - It is sometimes the fate of a tyrant to be obliged to take up his habitation in some of those cities which have been ruined by his wars, and in a house so ruinous as to be ready to fall into heaps. Ancient and modern history afford abundance of examples to illustrate this.
And he dwelleth - Or rather, “therefore he shall dwell.” As a consequence of his opposing God, and devoting himself to a life of sensuality and ease, he shall dwell in a desolate place. Instead of living in affluence and in a splendid city, he shall be compelled to take up his abode in places that have been deserted and abandoned. Such places - like Petra or Babylon now - became the temporary lodgings of caravans and travelers, or the abodes of outcasts and robbers. The meaning here is, that the proud and wicked man shall be ejected from his palace, and compelled to seek a refuge far away from the usual haunts of men.
Which are ready to become heaps - Which are just ready to tumble into ruin.