What a superb location for a performance! The flats on the north-east corner of Islington Green back onto a crummy atrium from which a staircase leads down to a vaulted, concrete pit (pictured below). A cross between a car park and a bull ring, or a subterranean version of a de Chirico painting, this huge chamber reminded me of the stark designs of the Italian modernist, Aldo Rossi.

Art historians can so easily get carried away looking for a thesis, a scaffolding on which to hang theories which can sometimes obscure as much as reveal. Not so here: as near perfect as might be imagined, this is a beautifully laid out, fresh look at a master painter, that lights up the National Gallery's basement exhibition space.

Sexy is an overused word in the arts but it’s an adjective you can’t help applying to some of Helaine Blumenfeld’s voluptuous marble sculptures as you run your fingers over their surfaces. These abstract bodily forms, often in the purest icing-white crystalline stone, are so tempting that you almost want to lick them. Licking is not actively encouraged but Blumenfeld is very keen that you touch and feel the surface of the work.

Brett Goodroad (b. 1979) is an artist and painter based in San Francisco. Born and raised in rural Montana, in 2012 he received the Tournesol Award, overseen by Sausalito’s Headland Center for the Arts. The Award recognises one Bay Area painter each year and financially assisted Goodroad and gave him studio space, allowing him to develop his distinctive, figurative, abstract style.

Fifteen years ago on a cold grey Saturday in mid-February, Trafalgar Square was filled with people marching to Hyde Park in opposition to the proposed invasion of Iraq. A million people gathered in London. Three times that number turned out in Rome. That day, across Europe and the rest of the world, between six to eleven million people participated in the largest coordinated anti-war rally in history.

Hie thee to Oxford, for it is doubtful that we will see the like of this exhibition again this side of the Atlantic. American art of the 1920s and 1930s was once disregarded in its homeland in favour of Francophile superiority, and once it fell into critical and commercial favour it became too expensive to move around at the beckoning of would-be international hosts.

Painted in ice-cream shades punctuated with vivid red, the series of portraits made by Picasso in the early weeks of 1932 are as dreamy as love letters. His mistress Marie-Thérèse Walther – we assume it is she – lies adrift in post-coital languor, her body spread before us as a delicious and endlessly fascinating confection.

The American artist, Joan Jonas is one of the pioneers of performance art. Now 82, she is being honoured with a Tate Modern retrospective and Ten Days Six Nights, a festival of live art in which many of her performances are being recreated.

It was always my dream to be an artist but I never expected to be a curator. Graduates considering vocations in critical and curatorial practice went to the Royal College of Art or studied art history at university. Not me: I trained at Chelsea College of Art and then went to the British School at Rome where I was the Abbey Scholar in Painting.

Sometimes you come across an artwork that changes the way you see the world. Tacita Dean’s film portrait of the American choreographer Merce Cunningham (main picture) is one such encounter.