The monument represents the point where Christopher Columbus landed in 1492.  It was his third stop in the new world. It is not known where Columbus first landed.  There is controversy but three islands are most likely - San Salvador Island, Samana Cay, or Plana Cays all within the Bahamas and near Long Island.

Christopher Columbus

Christopher Columbus (Italian: Cristoforo Colombo; Spanish: Cristóbal Colón; Portuguese: Cristóvão Colombo; before 31 October 1451 – 20 May 1506) was an explorer, navigator, and colonizer, born in the Republic of Genoa, in what is today northwestern Italy. Under the auspices of the Catholic Monarchs of Spain, he completed four voyages across the Atlantic Ocean that led to general European awareness of the American continents. Those voyages, and his efforts to establish permanent settlements on the island of Hispaniola, initiated the Spanish colonization of the New World.

• http://en.wikipedia.org/wiki/Christopher Columbus
• http://en.wikipedia.org/wiki/Guanahani