Six hundred of these forts were built or repaired by the emperor; but it seems reasonable to believe, that the far greater part consisted only of a stone or brick tower, in the midst of a square or circular area, which was surrounded by a wall and ditch, and afforded in a moment of danger some protection to the peasants and cattle of the neighboring villages.

[115] Yet these military works, which exhausted the public treasure, could not remove the just apprehensions of Justinian and his European subjects.

The warm baths of Anchialus in Thrace were rendered as safe as they were salutary; but the rich pastures of Thessalonica were foraged by the Scythian cavalry; the delicious vale of Tempe, three hundred miles from the Danube, was continually alarmed by the sound of war; [116] and no unfortified spot, however distant or solitary, could securely enjoy the blessings of peace.

The Straits of Thermopylae, which seemed to protect, but which had so often betrayed, the safety of Greece, were diligently strengthened by the labors of Justinian.

From the edge of the sea-shore, through the forests and valleys, and as far as the summit of the Thessalian mountains, a strong wall was continued, which occupied every practicable entrance.