The Bill of Rights
The first 10 amendments, called the Bill of Rights, were adopted in one year, 1791. They contain guarantees such as the right of the militia to bear arms, protection against unreasonable search and seizure, trial by jury, protection against self-incrimination, and so on. We take these individual liberties for granted, but as we see they were not included in the original Constitution. Individual liberties were an afterthought.