Benjamin Banneker: Washington D.C. Layout
Inventor Benjamin Banneker (1701-1806), the son of a former slave, worked as an astronomer, mathematician, surveyor, almanac author and farmer. Banneker is often credited with bringing the first working clock to America, though the claim is disputed. He was later appointed by Thomas Jefferson to be a part of a surveying team to lay out Washington, D.C. (AP Photo/Ron Edmonds)
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