What does it mean to be a great artist? Is it enough for your work to be admired, studied, emulated and quoted by contemporaries and subsequent generations, or is the value of art judged by a more complex set of criteria? By considering the extent of Rubens’ influence on artists from Rembrandt to Klimt, the Royal Academy is having a go at skinning a very old and troublesome cat: the elevation of Rubens from gifted confectioner to worthy Old Master.

Artangel continues to instigate extraordinary events in extraordinary places. Over the past two decades and more, directors Michael Morris and James Lingwood have helped generate major and ground-breaking work by Rachel Whiteread, Brian Eno, Laurie Anderson, Roni Horn, Jeremy Deller, Steve McQueen, Matthew Barney, Gregor Schneider, Francis Alÿs and many others. It's a long list. Their latest collaboration with PJ Harvey is no less thought-provoking and inspiring than the best of their unique collection of imaginative and risk-taking projects. 

From an apparently simple idea stems a very confusing exhibition. Here’s the idea: taking the seminal black square painted by Russian artist Kazimir Malevich as its starting point – in fact, a rectangle, with the small and undated Black Quadrilateral the first of three Malevich paintings – we are invited, over the span of a century and across a number of continents, to explore the evolution of geometric abstraction and its relation to “ideas of utopia”.  

The octogenarian Frederick Wiseman is a cult documentary film maker, with his own idiosyncratic and recognisable idiom. He has both vast experience and extraordinary independence. Characteristically, he makes long, prize-winning, fly-on-the-wall inside-the-institution films: reportorial, non-judgemental, loosely narrative, and wide in subject – from a hospital for the criminally insane, to a high school, the largest university in California (Berkeley), or the Paris Opera Ballet.

The ebullient presenter, writer and director Waldemar Januszczak opens his enthusiastic and proselytising hour-long film on Sir Peter Paul Rubens (1577-1640) by reading out a series of disparaging quotes from other artists.

I don’t think any of us will look at a museum in quite the same way after this dazzling documentary. For several years the Austrian film-maker Johannes Holzhausen and his team followed what seems to be scores of the working staff  inhabiting Vienna's Kunsthistorisches Museum (KMH), as they physically cared for the remarkable objects in their care, worried about how best to put them on view for the public, and met continually to discuss museum matters.

I must admit to feeling, briefly, just a little disappointed on first sight of Maggi Hambling’s Walls of Water, nine new paintings on show at the National Gallery. Perhaps it was the evocative title, which promises high drama and instant gratification, something obviously and extravagantly impressive. In short, I was expecting something bigger, an absurd statement because eight out of the nine canvases measure more than six by seven feet. And yet, they are small.

This huge exhibition is an awesome and terrifying compilation of photographs of the sites of conflict, and the remnants of wars and conflicts of all kinds – local, civil, short, long, global, technological, industrial and hand-to-hand. Taken from the mid 19^th century to the present, the images – hundreds, perhaps even well over a thousand –  are oblique and often incomprehensible or unidentifiable without the expansive wall captions. This is a show requiring us to read as well as look. 

David Hockney was continually rejuvenated by his transatlantic commuting. The painter, printmaker, draughtsman, photographer, and stage designer, was also a writer producing theories of seeing, and was fascinated by digital technology. Randall Wright's narration is set out in a series of short chapters in a montage-cum-collage of photographs, earlier films both amateur and professional, home video and recent interviews with the inhabitants of Hockney’s world today and in the past.

Printed large in glorious colour is a row of photographs of Russian women wearing bobble hats (main picture and pictured below). There’s a fuzzy red one, a woolly brown one, one with red stripes against black and another with raised white stripes. Seen from behind, these hand-knitted globes look like a newly discovered breed of sea anemone or a display of exotic cacti.