Horse at Water by Nic Fiddian-Green, Marble Arch
'An amazing horse's head sculpture, nose to pavement, 33ft high – I love the sheer incongruity of it. You stop in your tracks and wonder whose idea it was to put it there. Britain has a long history of equestrian statues, but many were excruciatingly tedious and ugly. Fiddian-Green has really reinvented the form.'
The Fourth Plinth Trafalgar Square
'Rather than any specific piece that has been displayed on the fourth plinth, it's the idea which is brilliant. Public art is a great thing. Everyone has access to this piece and you never know what's coming next.'
Material Gestures by Mark Rothko, Tate Modern
'I've solved almost all of my biggest dilemmas while sitting on the bench in the middle of this room. When I'm in there I lose myself and manage to find myself again. The only other place you have the opportunity to see that many Rothko pieces in one place is in New York.'
Three Studies for Figures at the Base of a Crucifixion by Francis Bacon, Tate Britain
'This triptych is one of my favourite paintings. The juxtaposition of the ancient mythology married together with Bacon's completely engrossing painting style is unmissable.'
Knife Edge Two Piece by Henry Moore, Westminster
'Moore's sculptures are timeless and so evocative. Simultaneously unique in design, but universal in terms of the impact they have on others. If I could own anything it would be a Henry Moore.'
Mariella Frostrup presents Leonardo Live from the National Gallery on 8 November from 7pm on Sky Arts and in Picturehouse cinemas nationwide (sky.com/arts). Leonardo da Vinci: Painter at the Court of Milan is at London's National Gallery from 9 November (nationalgallery.org.uk).
As told to Ianthe Butt.
