Why was the fall Constantinople considered the end of the European Middle Ages?

Constantinople’s Theodosian land walls were the most formidable defense of the Middle Ages, never falling to enemy action until the final fall of the city in 1453, when Medieval fortifications fell to early modern cannon. But that doesn’t mean that Constantinople was never taken by a hostile force.

i think they would live in caves or natural tunnels

answer; /// slavery should be outlawed in the new country, was part of the initial draft of the declaration of independence, but not part of the final