The Pharos at Alexandria was the last structure to be named on Antipater of Sidon's list of the Seven Wonders of the Ancient World. It was constructed at the beginning of the 3rd century BC, begun by Ptolemy Soter, the ruler of the Egyptian region after the death of Alexander the Great in 323 BC. It was impressive in its construction and scale, and legends claim that its light (a reflective mirror) was visible in the harbor from 35 miles away.
The Pharos (which has become a generic term for lighthouse) was actually located on the tiny limestone island of Pharos that sat in front of the harbor of what would become Alexandria. When Alexander the Great arrived in Egypt in 332 BC, Pharos was a shrine and home to Proteus, a sea god. When Alexander and his troops took Memphis (the ancient Egyptian capital) and defeated the occupying Persians, the Egyptian people were elated, and accepted him as their new Pharaoh.
As Alexander and his troops further explored their new territory, they happened upon a small fishing village called Rhacotis. Its strategic location (on the coast) caught Alexander's eye, and he proclaimed that a new capital city, Alexandria, was to be built there. Immense and opulent, this city would be home to beautiful art and architecture, as well as all of the most influential literature in ancient history in its fabled Library.
This new coastal capital of Egypt had a very horizontal quality about it, like the rest of Egypt. It also lacked any real landmarks that would aid ships in navigation there. Thus, the lighthouse was constructed on the tiny harbor island of Pharos as an aid to sailors. Later on, it would become a defensive monument as well.
The Lighthouse at Alexandria was designed by the Greek architect Sostratus of Cnidus. It was constructed of a light-colored stone that was reinforced with molten lead. This would have protected the walls from crashing ocean waves (this also helped it to become one of the longest-standing monuments of the list of wonders). It stood in three levels: a lower square level with a strong core to provide support, an octagon-shaped center level, and a circular level on top. At the peak of the lighthouse was a mirror that reflected the light of the sun at day, and a fire was lit each evening.
In the first century AD, the Pharos was believed to have become more than merely a navigational aid for sailing ships. Stories and legends claim that the lighthouse was used to set enemy ships ablaze in the harbor. Though many scholars refute this possibility due to technological limitations, recent experiments have shown that fires could have indeed been started using the reflective powers of the mirror and the sun (though probably not in as dramatic a fashion as reported by the ancients).
The Pharos at Alexandria stood and remained in use until 2 earthquakes, in 1303 and 1323, reduced it to rubble. In 1994, underwater archaeologists located some of the remains of the lighthouse in the Alexandrian Harbor, and more have recently been located using remote imaging. Some remains of the Pharos were also used in the construction of Fort Qaitbey in the 15th century, which stands on the very same spot to this day.