The ground-plan of Alexandria was traced by Alexander himself, but it was not completed until the reign of Ptolemy Philadelphus. Its circumference was about fifteen miles; the streets were regular, and crossed one another at right angles, being wide enough for free passage of both carriages and foot passengers. Its harbor could hold the largest fleet ever congregated; its walls and gates were constructed with all the skill and strength known to antiquity; its population numbered six hundred thousand, and all nations were represented in its crowded streets. The wealth of the city may be inferred from the fact that in one year sixty-two hundred and fifty talents, or more than six million dollars, were paid to the public treasury for port dues. The library was the largest in the world, numbering over seven hundred thousand volumes; and this was connected with a museum, a menagerie, a botanical garden, and various halls for lectures, altogether forming the most famous university in the Roman empire. The inhabitants were chiefly Greek, and had all the cultivated tastes and mercantile thrift of that quick-witted people. In a commercial point of view Alexandria was the most important city in the world, and its ships whitened every sea. Unlike most commercial cities, it was intellectual, and its schools of poetry, mathematics, medicine, philosophy, and theology were more renowned than even those of Athens during the third and fourth centuries. Alexandria, could it have been transported in its former splendor to our modern world, would be a great capital in these times. And all these cities were connected with one another and with Rome by magnificent roads, perfectly straight, and paved with large blocks of stone. They were originally constructed for military purposes, but were used by travellers, and on them posts were regularly established; they crossed valleys upon arches, and penetrated mountains; in Italy, especially, they were great works of art, and connected all the provinces. There was an uninterrupted communication from the wall of Antoninus through York, London, Sandwich, Boulogne, Rheims, Lyons, Milan, Rome, Brundusium, Dyrrachium, Byzantium, Ancyra, Tarsus, Antioch, Tyre, Jerusalem,--a distance of thirty-seven hundred and forty miles; and these roads were divided by milestones, and houses for travellers erected upon them at points of every five or six miles.