The Constitution of the United States is the fundamental law of the land. It was written at the Constitutional Convention that started its deliberations on May 25, 1787. The Convention finished its work on September 17 of that same year. The Convention met because many Americans believed that the Articles of Confederation, which was the first constitution of the United States, had not created a central government that was strong enough to make for a stable and long-lasting country. The delegates at the Convention wrote the Constitution to set up a framework for the government of the US that would be able to last for a long time.
The Constitution itself really does not guarantee fundamental rights to Americans. Instead, the Constitution proper lays out the structure of the American governmental system. It describes, for example, how Congress is to be selected and what powers it will have. The only fundamental rights explicitly guaranteed in the Constitution are the right to habeas corpus and the right to be free from ex post facto laws and bills of attainder. These are guaranteed in Article I, Section 9. The fundamental rights that we are more familiar with are actually guaranteed by the Bill of Rights, which consists of the first ten amendments that were added to the Constitution after it was ratified. Some of the fundamental rights guaranteed by the Bill of Rights are freedom of speech, of the press, of religion and the right to be free from warrantless searches and seizures.