What were the achievements of the Founding Fathers?

It's this country, that's what it is. We call them Founding Fathers because they founded a country. Collectively, that's their legacy. Of course, some of them had certain realms and did certain things over others (as in Thomas Jefferson leaves us with the Declaration and the Louisiana Purchase, Alexander Hamilton leaves us our financial system, James Madison gives us a Constitution, and so on and so forth), but to go into detail would be exhaustive. Their legacy, though, on the whole, was the United States.