The Smithsonian Institution was founded for the increase and diffusion of knowledge, on 10 August 1846, with funds from the Englishman James Smithson.
The Smithsonian, as it is known, is the world's largest museum, education, and research complex, with 19 museums and the National Zoo.
The majority of museums are located in the US capital with additional facilities in Virginia, Maryland and New York.
The Smithsonian Institution will mark its 175th anniversary by tapping into the spirit of a world fair.
Its original site, the Arts & Industries Building, will reopen to the public with FUTURES, an exhibit showcasing prototypes, robots, speculative fiction and new worlds, among other things.
There will be a range of events and activities to mark the anniversary