On this day in 1492, after sailing across the Atlantic Ocean, Italian explorer Christopher Columbus sights a Bahamian island, believing he has reached East Asia. His expedition went ashore the same day and claimed the land for Isabella and Ferdinand of Spain, who sponsored his attempt to find a western ocean route to China, India, and the fabled gold and spice islands of Asia. Columbus was born in Genoa, Italy, in 1451. Little is known of his early life, but he worked as a seaman and then a maritime entrepreneur. He became obsessed with the possibility of pioneering a western sea route to Cathay (China), India, and the gold and spice islands of Asia. At the time, Europeans knew no direct sea route to southern Asia, and the route via Egypt and the Red Sea was closed to Europeans by the Ottoman Empire, as were many land routes. Contrary to popular legend, educated Europeans of Columbus' day did believe that the world was round, as argued by St. Isidore in the seventh century. However, Columbus, and most others, underestimated the world's size, calculating that East Asia must lie approximately where North America sits on the globe (they did not yet know that the Pacific Ocean existed).