The Smithsonian Institution, an Establishment for the “increase & diffusion of knowledge” was founded from a bequest to the United States by the British scientist James Smithson (1765-1829). Mr. Smithson named his nephew as beneficiary in his last will and testament and stipulated that if the nephew should die without heirs the estate should go to the United States of America. James Smithson died in 1829, his nephew; Henry James Hungerford died without heirs in 1835. The President of the United States at that time, Mr. Andrew Jackson informed Congress of this bequest, which amounted to 100,000 gold sovereigns, when recoined is US currency; over 500,000$ (today with inflation, approximately 10,100,000.00$). http://siarchives.si.edu/history/exhibits/historic/history.htm#sib
As to why Smithson gave all his estate remains unknown, he never traveled to the United States and no one seemed to have correspondence with him. After a debate as to whether the federal government had the authority to accept the gift, Congress accepted the legacy bequeathed to the nation and pledged the faith of the United States to the charitable trust July 1, 1836. Eight years later, Congress passed an act establishing the Smithsonian Institution, a public/private partnership, and the act was signed into law on August 10, 1846 by James Polk.
The architecture of the Smithsonian Institution Building has resulted in its informal name “The Castle”, it was completed in 1855 by architect James Renwick, Jr. Many of the Institution’s other buildings are historical and architectural landmarks.
The Museums http://www.si.edu/museums/
Research Centers http://www.si.edu/research/
Besides the Museums and Research Centers, the Smithsonian shares artifacts and other programs with 160 museums and educational organizations. https://affiliations.si.edu/MainPage.asp
The Smithsonian Institution, the world’s largest museum complex and research organization!