The Lighthouse of Alexandria
Alexandria, Egypt was one of many cities founded by Alexander the Great, and one of the few that still bears his name. The site was chosen carefully, away from the Nile Delta where silt build up from the river would eventually block a harbor. Alexander died in 323 BC, and the city was completed under Egyptian ruler Ptolemy Soter. The city needed a means to guide trade ships to the busy harbor, so Ptolemy authorized building the lighthouse in 290 BC on the island of Pharos, giving the name "pharos" as a synonym for lighthouse in many languages. A mole of land was built between the island and mainland and lighthouse construction was completed in about 20 years. Standing about 150 meters high, it was the tallest structure in existence at the time except for the pyramids.
Unlike modern day lighthouses, the structure was a square, narrow, building tapering with successive sections narrower than those below. It resembled a modern skyscraper more than the narrow cone design we normally associate with lighthouses. It had many ornaments and statues, and seems to have been a tourist attraction. The beacon room at the top contained a furnace and a curved mirror, probably polished bronze, that provided smoke during the day and light after dark that could be seen many miles out to sea.
The pharos was damaged many times by earthquakes and repaired until finally a severe earthquake in 1303 AD put it out permanently. Much of the pharos remained in ruins until about 1480 AD, when a small fortress was built on the site. The limestone fortress still stands, partially constructed with granite stones from the pharos. The granite blocks that form the front portal and other parts of the fortress differ in color and texture to the limestone fortress and can be easily seen in the photos. Link.