 Angered by this rejection and the city's loyalty to Persian king Darius the Great, Alexander started his Siege of Tyre despite its reputation as being impregnable.However, the Macedonian conqueror succeeded after seven months by demolishing the old city on the mainland and using its stones to construct a causeway to the island.This isthmus increased greatly in width over the centuries because of extensive silt depositions on either side, making the former island a permanent peninsula - based on the ruins and rubble of Palaetyrus.