FGS
The whole city was built out on the beach, for all practical purposes; the underlying strata just slid the whole works into the drink, as if it were on a tobaggan.
Seven Wonders of the Ancient World
The Lighthouse (Pharos) of Alexandria
Alaa K. Ashmawy
http://ce.eng.usf.edu/pharos/Wonders/pharos.html
In AD 956, an earthquake shook Alexandria, and caused little damage to the Lighthouse. It was later in 1303 and in 1323 that two stronger earthquakes left a significant impression on the structure. When the famous Arab traveler Ibn Battuta visited Alexandria in 1349, he could not enter the ruinous monument or even climb to its doorway... In 1166, an Arab traveler, Abou-Haggag Al-Andaloussi visited the Lighthouse. He documented a wealth of information and gave an accurate description of the structure which helped modern archeologists reconstruct the monument. It was composed of three stages: The lowest square, 55.9 m (183.4 ft) high with a cylindrical core; the middle octagonal with a side length of 18.30 m (60.0 ft) and a height of 27.45 m (90.1 ft); and the third circular 7.30 m (24.0 ft) high. The total height of the building including the foundation base was about 117 m (384 ft), equivalent to a 40-story modern building. The internal core was used as a shaft to lift the fuel needed for the fire. At the top stage, the mirror reflected sunlight during the day while fire was used during the night. In ancient times, a statue of Poseidon adorned the summit of the building.