The Nile Delta is formed by the mainstream of the Nile entering northern Egypt, then spreading near Cairo and merging into the Mediterranean Sea. It is one of the largest deltas in the world, with Cairo as its apex, Alexandria in the west and Port Said in the east, with a coastline of 230 kilometers and an area of about 24,000 square kilometers. The Nile Delta is fertile and densely populated, and it is the birthplace of ancient Egyptian civilization. It is also one of the regions with the highest population physiological density in the world.