Marc Quinn's sculpture of the disabled artist Alison Lapper was displayed from September 2005 until October 2007.
Lapper, who was born with no arms and shortened legs due to a congenital disorder, posed naked for Quinn when she was eight months pregnant.
"Alison Lapper Pregnant" was replaced with a very different artwork - an architectural model of a 21-story building.
The coloured glass sculpture by German artist Thomas Schutte, "Model for a Hotel 2007" was unveiled in November 2007 and occupied the plinth until the end of May 2009.
Next came Anthony Gormley's "One and Other" - a "living monument" which involved members of the public taking to the plinth.
The space was occupied by different people - chosen by ballot - every hour, 24 hours a day, for 100 days.
From 2010 to 2012, the plinth was home to Yinka Shonibare's "Nelson's ship in a bottle" which commemorated the Battle of Trafalgar.
And currently in position is a giant bronze sculpture of a boy astride a rocking horse. It is called "Powerless Structures Fig 101".
More top news
Clear tonight with temperatures falling quickly. Light winds and lows of 5C.
An elderly and vulnerable man is fighting for his life after being mugged while riding a mobility scooter.
The latest disruption on an increasingly delay-affected Underground system was on the Central line.