King Darius of Persia sent a huge fleet to conquer Athens, after the Greeks had been assisting a Persian province in Asia Minor in revolt against the Persians. The fleet was destroyed in 492 B.C. by a huge storm as it rounded the Athos Peninsula .
A second attack by Darius was defeated at Marathon by Athenian warriors.
Darius' son Xerxes decided to conquer Greece also, and in 480 B.C. began preparations. So that his fleet would not meet the same fate as Darius' first fleet, he ordered his army and those of his allies to build a canal across the one and a quarter mile wide Athos Peninsula. The work went on for three years, and when completed the canal was 100 feet wide at the surface, 45 feet deep and 50 feet wide at the bottom. This was wide enough for two warships to pass abreast. The Persian fleet passed through the canal, and then the canal was largely abandoned, and was silted in
over the years. Xerxes went from the canal to burn Athens, but his fleet was destroyed by the Athenian navy in the Battle of Salamis. Never maintained, the canal fell into disuse quickly. Its existence had been debated by historians, but recent studies have confirmed its location at the narrowest point on the peninsula. The canal can be seen as a line of green trees between the two red dots.