Fourth Plinth

The exhibition Fourth Plinth: Contemporary Monument currently at London's ICA (Institute of Contemporary Arts) is a documentation of the thirteen years' history of this art commission in Trafalgar Square.  Some of the projects exhibited have been materialized; some have not.  Here are my favourite ones:

Rachel Whiteread's 2001 (built) Untitled Monument:

Anish Kapoor's 2008 (proposed) Sky Plinth:

Mariele Neudecker's (proposed) It's Never Too Late And You Can't Go Back: