The Tower of Abusir, also called the Lighthouse of Taposiris Magna, and Burg El-Arab or the Arab Tower, is a Ptolemaic structure, located on the main road from Alexandria, Egypt, to the ancient towns of Marsa Matrooh (Mersa Matruh, in Egypt) and Cyrene (Shahhat, Libya). The tower is located some two kilometers (1.2 miles) from the Mediterranean coastline, and 1.5 km (.9 mi) from the Mareotis lake harbor town of Taposiris Magna. Most scholars agree that the tower functioned as a funerary monument, built as a 1/10th scale quasi-replica of one of the original Seven Wonders of the World, the Pharos Lighthouse of Alexandria. Unlike its famous predecessor, the Abusir Tower still stands today, having been extensively restored in the 20th century, and the view from the top overlooks the Mediterranean Sea and the ruins of the Taposiris Magna's harbor.
The tower lies about 500 meters (1600 feet) from Taposiris Magna's Temple of Osiris, and in the middle of an enormous Greco-Roman cemetery. Burials within the cemetery both predate and postdate the tower's construction. The Tower of Abusir is believed to have been built for the pharaoh Ptolemy II "Philadelphus" (284-246 BC).
Like the Pharos Lighthouse, the Abusir Tower has three stories: a square first floor measuring 10.75x10.75 m (35.2x35.2 ft); an octagonal second story, 10.65 m (35 ft) high; and a smaller, cylindrical third story perched on the top. Directly beneath the tower is a funerary hypogeum. A spiral staircase could be followed up the internal wall of the building; it has been replaced in the restoration with an internal wooden staircase.
At a total original height of some 17 m (55 ft), the building has several structural similarities to the far more famous Pharos lighthouse, albeit on a smaller scale. The Pharos lighthouse was built by the Greek architect Sostratus in the 3rd century BC, and destroyed by an earthquake in the 14th century AD. Fortunately, the amazing structure was described in some detail by Arabic and Spanish travelers; and based on those descriptions, scholars believe the Abusir tower was built modeled on Pharos, at approximately 1/10th scale.
This similarity to descriptions of the Pharos Lighthouse led early scholars to hypothesize that the function of the Abusir Tower was also similar. The Pharos Lighthouse was a beacon to sailors on the Mediterranean looking for Alexandria; the Abusir Tower was thought to have been a lighthouse for sailors on Lake Mareotis.
However, there are differences which make the tower's function somewhat in doubt. A stone socle half meter high supporting each segment of the tower was included in the structure, which was not a part of the Pharos lighthouse, and there are no windows in the Abusir Tower. The Pharos lighthouse had sloping ramps for the use of mules to carry fuel for the light to the top, and a double spiral staircase: these features are not seen at Abusir.
If the Abusir tower was a lighthouse, said early scholars, it might have functioned as a beacon tower to warn mariners of the rocky headland, or as one of a series of signal towers placed along the coast. The location between Taposiris and its immediate neighbor city Plinthine led some to believe it served as an indicator of the separate ports to mariners (Taposiris to the west of the tower, Plinthine to the east).
However, these uses truly require a functioning beacon as part of the tower, and such a beacon would require a huge and steady supply of fuel, and a huge space at the top to store it. The space at the top of the Abusir tower is too small to hold adequate fuel, and the narrow internal staircase would have prohibited carrying the fuel up repeatedly.
Further, at 1.5 km from the lakeshore, the tower is in the wrong location for a sea beacon, and as a watchtower the lack of windows would seem odd, and the presence of the pylons from the Taposiris Magna temple would hamper view to the west.
In a 1974 article in the journal Harvard Studies in Classical Philology, Fawzi el Fakharani suggested that the most likely function of the tower was as a funerary monument; other scholars have agreed, citing the proximity of the Temple of Osiris and connecting the two culturally and temporally. By the way, el Fakharani's article also includes a pre-restoration photo of the tower, so if you'd like, you can get a good idea on how much of it is the real thing.
el Fakharani F. 1974. The "Lighthouse" of Abusir in Egypt. Harvard Studies in Classical Philology 78:257-272.
Elnashai AS, Di Sarno L, and Carter MD. 2006. New light on an ancient illumination: The Pharos of Alexandria. International Journal of Nonlinear Sciences and Numerical Simulation 7(2):137-148.
Kassem A, and Gouda M. 2008. A Revival of the Site of Abousir (Taposiris Magna). WSEAS International Conference on Cultural Heritage and Tourism. Heraklion, Crete. p 71-76.