History of the Peloponnesian War

In this way the Athenians walled their city in a short time.

And the building still slows even now that it was executed in haste; for the foundations are laid with stones of all kinds, and in some places not wrought together, but as the several parties at any time brought them to the spot: and many columns from tombs, and wrought stones, were worked up in them. For the enclosure of the city was carried out to a greater extent on every side; and for this reason they hurried on the work, removing every tiling alike.

Themistocles also persuaded them to build the remaining walls of the Piraeus, (they had been begun by him before, at the time of his office as archon, which he had held for a year over the Athenians,) thinking that the site was a fine one, as it contained three natural harbours; and that by becoming a naval people they would make a great advance towards the acquisition of power.

For he was the first who ventured to tell them that they must apply closely to the sea;

and he began immediately to assist in paving the way for their empire. It was by his advice that they built the walls of that thickness which is still seen round the Piraeus; for two waggons meeting each other brought up the stones. And in the inside there was neither rubble nor mortar, but large and square-cut stones wrought together, cramped on the outside with iron and lead. But only about half of the height he intended was finished.

For he wished by their great dimensions and thickness to keep off the attacks of their enemies; and thought that the protection of a few, and those the least efficient troops, would be sufficient, while the rest would go on board their ships.

For to the navy he paid the greatest attention; seeing, I suppose, that the approach of the king's forces against them was easier by sea than by land: and he considered the Piraeus more serviceable than the upper city, and often advised the Athenians, in case of their ever being hard pressed by land, to go down into it, and defy the world with their navy.

Thus then the Athenians were enclosed with walls, and began to furnish themselves with other buildings immediately after the retreat of the Medes.