Xerxes' pontoon bridges
Xerxes' pontoon bridges were constructed in 480 BC during the second Persian invasion of Greece (part of the Greco-Persian Wars) upon the order of Xerxes I of Persia for the purpose of Xerxes' army to traverse the Hellespont (the present-day Dardanelles) from Asia into Thrace, then also controlled by Persia (in the European part of modern Turkey). The bridges were described by the ancient Greek historian Herodotus in his Histories, but little other evidence confirms Herodotus' story in this respect.