The plinth, in the northwest corner of the square, was built in 1841 to hold an equestrian statue of King William IV, but the money ran out and it was left empty.
Having been empty and unused for a century and a half, it was first used to host temporary sculptures in 1998, after which the Royal Society of Arts launched the Fourth Plinth Project. David Shrigley's work will follow a long line of artists and sculptors who have graced the stage of the fourth plinth.
Some have been quirky, others more serious. Here are our top ten.