 The "factorij" was a small fortification which served as a trading post and warehouse.Henry Hudson explored what would be known as the Hudson River for the Dutch in 1609, including Castle Island which was at the center of Native American fur trading routes from the interior.Hendrick Christiaensen chose Castle Island to build Fort Nassau, in 1614 or 1615 as a dual warehouse and military defense structure and named the fort in honor of the stadtholder of the United Netherlands, who was of the House of Orange-Nassau.