"The Constitution preserves the advantage of being armed which Americans possess over the people of almost every other nation where the governments are afraid to trust the people with arms."
~James Madison
The word "revolutionary" can mean many things, such as "new", "innovative", and "original".  All of these words describe the unique and remarkable government that was established in America by The Constitution.
Though The Articles of Confederation was America's first constitution, the modern day constitution (known as The Constitution) is the revolutionary symbol in America. This is because the modern constitution is unique and brilliant in that it set up the nation's strong form of government that is still being used today.
America was the first country to run themselves using a written constitution to set up its government

The Articles of Confederation was America's first constitution, but there were many issues that needed to be addressed

The federal government had very limited powers and was not accomplishing their goals in helping the nation

It was decided to build an entirely new constitution, which is the one that is still being used today

The new constitution was created with the knowledge that the rights of individuals were at risk if the government was too strong and had insufficient limitations

So the framers created balance and control within the government so it would not become too powerful, but would still have the ability to run the nation