One of the earliest surviving sculptures by Barbara Hepworth is a toad made from a khaki-coloured, translucent stone; you can imagine it cool and heavy in your hand, not so very different from the animal itself, in fact. Made nearly 30 years later, the monumental sculptures carved from African guarea wood are almost unbearably touchable, each one with its dark, glossy exterior cracked open to reveal an inside as creamy as a conker. But while we are denied the pleasure of touching these objects, looking at Hepworth’s work is in itself a gloriously tactile experience.

Peter Zinovieff: Electronic Calendar – The EMS Tapes

Trying to pigeonhole Apocalypse, girl, Norwegian artist Jenny Hval’s third album under her own name, is like trying to grab onto a snake that is in the process of shedding its skin. It’s a simile that you can’t help thinking Hval would enjoy: “Kingsize”, the spoken word performance poem that opens the album, employs what might be an extended metaphor about bananas rotting in her lap – although it could just be about bananas.

Modigliani’s short life was a template for countless aspiring artists who, in the period after his death in 1920, were only too willing to believe that a garret in Montmartre and a liking for absinthe held the secret to creative brilliance. While Modigliani certainly compounded poor health with a ruinous drink and drug addiction, this exhibition plays down his reputation as a hellraiser, suggesting instead an altogether quieter, although no less romantic character.

In 1967 when she produced Syncopated Rhythm (main picture), Sonia Delaunay was 82; far from any decline in energy or ambition, the abstract painting shows her in a relaxed and playful mood. Known as The Black Snake for the sinuous black and white curves dominating the left hand side, this huge, two and a half metre wide canvas is deliciously varied.

Pierre Boulez sits in the back of a car as it drives across Westminster Bridge. He is talking about the audience appeal of his music, and he is characteristically direct. If the performance is good, and the situation is right, he insists, then audiences will come. That was back in 1968. The interview was featured in one of the documentaries that began today’s event, and it proved prescient. Boulez at 90, the day-long festival of music by the BBC Symphony Orchestra's former chief conductor, was well planned (by the BBCSO) and well performed.

I first saw Spectres last October at the 10^th birthday celebrations for their label, Sonic Cathedral. That night, they struck me as noisy, spiky and fun. If that sounds like faint praise, it really wasn't meant to be – noisy, spiky fun is in my all-time top three funs. Now, they've gone from bottom of the bill to headline act in less than six months on the back of an album so incendiary it should come wrapped in a fire blanket (well, it beats a tote bag any day) and, oh my… how they have grown. Really, this band’s development needs to be measured in cat years.

Here is an exhibition that tells us how something we now take totally for granted actually came about: how our love affair with the Impressionists was masterminded by an art dealer, Paul Durand-Ruel (1831-1922). He was a prime mover in inventing the way art is dealt with by commercial galleries and even museums, and is credited as the inventor of the modern art market.

So, Picasso’s last words turned out not to be, “Drink to me. Drink to my health. You know I can’t drink anymore” – yes, those famous last words that inspired a Paul McCartney dirge – but were, according to this TV biography looking at Picasso’s women and how each significant relationship informed the direction of his work, “Get me some pencils”. A more prosaic request, certainly, but he died in bed, aged 93, his pencils delivered and drawing to the last. It was a good and fitting end.

Russia’s national gallery, the Tretyakov, bears the name of its founder Pavel Tretyakov, the 19th-century merchant who bequeathed his huge collection of Russian art to the city of Moscow in 1892. His bust stands proudly overseeing the entrance to the gallery’s old building, a fine, purpose-built example of early Russian 20th-century architecture.