The twelfth-century traveler Ibn Jubayr described the harbor at Tyre in Lebanon and explained how seasonal winds affected travel on the Mediterranean:

the strength and impregnability of Tyre is more marvelous than is told of. It has only two gates, one landwards, and the other on the sea, which encompasses the city save on one side. The landward gate is reached only after passing through three or four posterns in the strongly fortified outer walls that enclose it. The seaward gate is flanked by two strong towers and leads into a harbor whose remarkable formation is unique among maritime cities. The walls of the city enclose it on three sides, and the fourth is confined by a mole bound with cement. Ships enter below the walls and there anchor. Between the two towers stretches a great chain which, when raised...