Benjamin Banneker was born in 1731. His mother and grandmother were both married to slaves. Benjamin was very intelligent. When he was around 20 years of age, he obtained a pocket watch. He carefully took it apart, studying how each piece worked. Then he built a near completely wooden clock. In 1791, Banneker had the idea to make an almanac. When he was unable to get it published, it was sent to Thomas Jefferson, which proved that African Americans were equal to "white" people. Late in that year, the 1792 almanac was published. He was an inventor, mathematician, and author. He helped LaFantí design Washington D.C. Because he had a photographic memory he was able to draw the plans from memory when LaFantí left the project unfinished. Benjamin Banneker died in 1806.