Alexandria was located on a fault line. A fault line is where tectonic plates meet. When these plates move, they cause earthquakes. The earthquakes that these tectonic plates caused destroyed Alexandria. They also caused the land that Alexandria was located on to sink into the surrounding sea. The Ptolemies had built their palaces on the shore of their great harbor. As the land sank, the Royal Quarter of the Ptolemies submerged. The sea also swallowed Cleopatra's Palace.
No one knows what Cleopatra's Palace actually looked like. Many artists have tried to recreate the palace through paintings. That used to be the closest we could come to seeing her great palace. However, in recent years, archeologists have been exploring the bay of modern Alexandria.
Franck Goddio has been interested in the secrets of the sunken Alexandria since 1980. It took Goddio until 1992 to get all the permits he needed. First, he did a general survey of the area. After a few failed attempts, storage jars were found. According to Strabo's ancient text, these jars were on the only island off the Great Port of Alexandria, Antirhodos.
In 1996, 3,550 separate dives found traces of ancient quays, statue fragments, and hieroglyphic inscriptions. In 1997, a road was even discovered. Large, squared stones were also found. These are the remains of a building. It's located in an area, which is supposed to be the Royal Quarter. Near by, the remains of other fallen buildings were found. Because whole buildings can't be brought to the surface, these weren't studied any more than to identify them as a few of the Ptolemy Palaces.