Six international artists have been shortlisted to come up with a temporary artwork for the vacant fourth plinth in Trafalgar Square.
Modern art has been displayed on the empty plinth
The square in central London which contains Nelson's Column was built during the 1840s.
Equestrian statues of British Empire heroes occupy its three other corners - two of 19th Century generals and one of King George IV.
But the fourth has stood empty since King William IV died without leaving enough funds to have his own statue erected, and no one else stepped in.
Three years ago an independent review group chaired by the author Sir John Mortimer decided the plinth should be used for an ever-changing display of artworks.
Now London's mayor Ken Livingstone, who has had the square transformed into a partly pedestrianised area, has developed the Fourth Plinth Project.
A commissioning group has selected six artists - Chris Burden, Sokari Douglas Camp, Stefan Gec, Sarah Lucas, Thomas Schutte and Marc Quinn.
The winning work will be displayed on the plinth for between 12 and 18 months as the first piece of art in a rolling programme.
Mr Livingstone said: "The Fourth Plinth Project is integral to my vision for Trafalgar Square becoming London's new focal point for cultural excellence and activity.
"This shortlist of six internationally renowned artists represents a great range of vision and approach.
He said the public would be able to take part in the commissioning process by expressing their preferences on the shortlisted proposals.
Working models of the works would go on public display in the Sainsbury Wing foyer at the National Gallery during December 2003 and January 2004.
Visitors will be able to record their opinions there and on a special website.
The winner will be announced in the spring.