Tyre is an ancient Phoenician port city which, in myth, is known as the birthplace of Europa (who gave Europe its name) and Dido of Carthage (who gave aid to, and fell in love with, Aeneas of Troy). The name means 'rock' and the city consisted of two parts, the main trade centre on an island, and 'old Tyre', about a half mile opposite on the mainland. The old city, known as Ushu, was founded c. 2750 BCE and the trade centre grew up shortly after. In time, the island complex became more prosperous and populated than Ushu and was heavily fortified. The prosperity of Tyre attracted the attention of King Nebuchadnezzar II of Babylon who lay siege to the city for thirteen years in the 6th century BCE without breaking their defenses. During this siege most of the inhabitants of the mainland city abandoned it for the relative safety of the island city. Ushu became a suburb of Tyre on the mainland and remained so until the coming of Alexander the Great. The Tyrians were known as workers in dye from the shells of the Murex shellfish. This purple dye was highly valued and held royal connotations in the ancient world. It also gave the Phoenicians their name from the Greeks - Phoinikes - which means "purple people". The city-state was the most powerful in all of Phoenicia after surpassing its sister state Sidon. Tyre is referenced in the Bible in the New Testament where it is claimed that both Jesus and St. Paul visited the city and remains famous in military history for Alexander the Great's seige.