One of the greatest engineering feats of ancient times, Xerxes' bridge over the Hellespont was actually two bridges. See The Persian Wars and this Launchpad for more background. Here is an image of the Hellespont today, and a satellite image as well. This is a view of how the Hellespont might have looked in 480 BCE.
You will now rebuild that famous set of bridges.
Xerxes's Phoenician and Egyptian engineers built two bridges across the Hellespont, the waterway between Asia Minor (modern Turkey) and Greece. This waterway also connects the Black Sea to the Aegean part of the Mediterranean Sea.