(Off the shores of Alexandria, the city of Alexander the Great, lie what are believed to be the ruins of the royal quarters of Cleopatra. It is believed that earthquakes over 1,500 years ago were responsible for casting this into the sea, along with artifacts, statues and other parts of Cleopatra’s palace. The city of Alexandria even plans to offer underwater tours of this wonder.
Jason de Caires Taylor’s underwater sculpture garden in Cancun. Constructed out of concrete and steel, and bolted to the ocean substrate, the works here act as artificial reefs that provide “an ideal habitat for filter feeding organisms.” http://www.dedeceblog.com/2010/10/13/cancun/