The lighthouse of Alexandria stood on the island of Pharos. The Pharos of Alexandria is one of the Seven Wonders of the World and the most famous lighthouse in antiquity. It was most probably begun under Ptolemy I Soter a Macedonian general of Alexander the Great and was finished during the reign of Soter's son Ptolemy II of Egypt in about 280 BC.
Much of what we know about the structure of the lighthouse comes from a German scholar named Hermann Thiersch, who authored a book on this topic, one of the best reference works on Pharos Lighthouse.
It is generally reckoned that the Lighthouse was a tower over 100 metres tall standing on the eastern tip of Pharos island and that it was constructed in three stages: the first was square, the second octagonal and the last circular. Access to the entrance was up a long vaulted ramp. From there, a spiral staircase led up to the many chambers and it was perhaps used by beasts of burden to carry fuel to the third storey where the fire burned on the summit. 
It gave its name "Pharos" to all the lighthouses in the world.