In the distance to the left stands Independence Hall, where the Declaration of Independence was signed in 1776. Later on, when it became clear that the United States of America was not working out under the Articles of Confederation, delegates gathered there again to work on a new basic document, called the Constitution. The Constitution was adopted in 1787, and went into force the next year by ratification by nine of the thirteen states; the United States became the first country in the world to run a constitutional government, rather than one based on common customary law.

In front is a marker with the First Amendment to the Constitution, ratified in 1791. While the Constitution had spelled out the inner workings of the three branches of the US federal government, it had not explicitly spelled out the rights that the people had under the new country's laws, and given that the US had broken away from the British crown over its infringement of people's freedoms, it was necessary to enumerate people's explicit rights. To that end, ten amendments were tacked on to the Constitution in the early 1790s, and they form the Bill of Rights. Over the years, an additional seventeen amendments were added to the Constitution to further define rights and responsibilities, including the end of slavery, extension of voting rights to people of color and women, clarification of the income tax, the Prohibition on alcohol (and its repeal), and term limits on the President.

The First Amendment does a lot to establish the basic rights of Americans, by guaranteeing them the right to free exercise of religion, a secular government, freedom of speech, freedom of the press, freedom of assembly, and freedom to petition the government for righting its wrongs.

The United States Constitution can be amended with a two-third majority of Congress or a constitutional convention, followed by ratification by three-fourths of the states. One provision of the Constitution - assigning two seats per each state to the United States Senate, regardless of the state's population - is prohibited from amendment.