Final answer:
The most important discovery during the Age of Exploration was Columbus' discovery of the Americas, which led to major shifts in global trade, population relocation, and cultural exchanges, though Magellan's circumnavigation of the globe was also a key milestone in advancing navigation and understanding of the world.
Step-by-step explanation:
When considering the most important discovery of the Age of Exploration, there are multiple contenders. However, one of the key milestones was Columbus' discovery of the Americas. This event was significant as it revealed a whole new continent to the Europeans, which had immense consequences, including the Columbian Exchange, massive movements of people, and the reorientation of global trade.
Another seminal event was Magellan's circumnavigation of the globe, confirming the Earth's roundness and the vastness of the oceans, which greatly advanced European navigation and understanding of the world.
The opening of a sea route to India by Vasco da Gama established a direct trade link with Asia, bringing wealth to Portugal and altering European commerce.
While Marco Polo's travels to Asia preceded the Age of Exploration, they certainly inspired later explorers but do not fall within this period.
In summary, each of these discoveries had a significant impact on the course of world history, with Columbus’s and Magellan’s discoveries among the most transformative in terms of their immediate and long-term effects on global interactions.