His tomb is in the SI's castle in the DC mall...............

James Smithson, MA, FRS (5 June 1765 – 27 June 1829) was an English chemist and mineralogist. He was the founding donor of the Smithsonian Institution.

Smithson was the illegitimate child of the 1st Duke of Northumberland, and was born secretly in Paris, possibly in the Pentemont Abbey,^[1] as Jacques-Louis Macie (later altered to James Louis). Eventually, he was naturalized in England and attended university, studying chemistry and mineralogy. At the age of twenty-two, he changed his surname from Macie to Smithson, his father's pre-marriage surname.^[2] Smithson traveled extensively throughout Europe publishing papers about his findings. Considered a talented amateur in his field, Smithson maintained an inheritance he acquired from his mother and other relatives.

Smithson was never married, and had no children; therefore, when he wrote his will, he left his estate to his nephew, or his nephew's family if his nephew died before Smithson. If his nephew was to die without heirs, however, Smithson's will stipulated that his estate be donated to the founding of an educational institution in Washington, D.C., in the United States. In 1835, his nephew died, and could not claim to be the recipient of his estate; therefore, Smithson became the founding donor of theSmithsonian Institution in Washington, D.C. – despite having never visited the United States.