Ellen Gallagher is obsessed by the issue of black cultural identity; but if that sounds tedious or tendentious, think again. She explores her theme in work that is so varied, so beautiful and so humorous that the furrow she ploughs seems more like an endless opportunity than a narrow limitation.

Saloua Raouda Choucair began her career as a painter, initially studying under Lebanon’s two leading landscape artists, Mustafa Farroukh and Omar Onsi. In the late 1940s, she trained in the studio of Fernande Léger while studying at the Ecole des Beaux-Arts in Paris. Her exposure to art in her native Beirut would have given no hint of the vibrant modernism she would embrace, albeit several decades after Europe had been all aflush with the new.

When I visited Rachel Whiteread two years ago, there were two old sheds gathering dust in her basement as though waiting to be loved and put to use. Why was she cluttering up her studio with such large and intrusive objects, I wondered? “Things fester,” she told me by way of explanation. “I like to mull things over, so they might lie about for years. It’s to do with me noticing them; they need to relate to my train of thought and investigation.

“I don’t like the family Stein; There is Gert, there is Ep and there’s Ein; Gert’s Poems are bunk, Ep’s statues are punk, And nobody understands Ein” (Anon).

Jacob Epstein (1880-1959) did indeed sculpt Albert Einstein when the physicist was briefly interned in London on his way to America in 1933; Epstein’s bust of the quizzical shock haired scientist is currently on view at the Victoria and Albert. Epstein described his subject, already legendary, as humane, humorous and profound and was particularly struck by his hair going every which way.  

There was a time when the art of the Low Countries was considered to be very lowly and base indeed. It was the high art of Italy that counted if you were a person of culture and breeding. Not for you the carousing common folk of Jan Steen, or those watery flatlands of Van Goyen, touched with too much bleak realism. It was the arcadian Campagna of Claude – like Poussin a Frenchman but with the Rubicon flowing through his veins – that you looked to.

Ambika P3 is a windowless, cavernous basement once used to test concrete for huge building projects – the Channel Tunnel among them – now ingeniously recycled as a kunsthalle gallery / performance space.  Thus it is strikingly appropriate for its current incarnation.

It’s an instinct of curators to put the pieces back together, to reintroduce works of art which time and market forces have scattered to the four winds. In recent memory, exhibitions have reunited in one space all of Monet’s haystacks, Cézanne’s card players and, in the case of the National Gallery’s momentous Leonardo show, both versions of The Virgin on the Rocks. A new exhibition opened this week in Florence which takes the business of synthesis to the next level.

"In the midst of life we are in death.” This is a line we may feel compelled to reverse as we encounter the first exhibits in the British Museum’s extraordinarily powerful exhibition, for this is a display vividly bringing the dead to life in the very midst of their extraordinary demise. But then, “ashes to ashes” conveys particular resonance, too, for we all know that Pompeii, a town situated in the Bay of Naples, and its lesser known, less populous neighbour Herculaneum, were both covered in a thick layer of ash when Mount Vesuvius erupted in AD79.

It’s not often that a performance’s technological properties leaves you simply slack-jawed. Robert Wilson’s very long Swedish-language version of Strindberg’s A Dream Play did – at the same venue, though this time in 2001 – when the surtitle machines broke down (the audience gave an audible gasp of horror and then settled to its collective fate), but that was for altogether different reasons. Compared to what Ryoji Ikeda and his team are capable of, even the beautiful crispness of Kraftwerk’s stage shows fade into the realm of the bland.

Rodin’s The Burghers of Calais have decamped from their usual perch next to the House of Lords to cosy up to the work of Henry Moore. They can be found at Moore’s home and studio at Perry Green in Hertfordshire, in a tellingly succinct anthology of the towering giants of modern European sculpture. At first glance Rodin’s extraordinary evocations of energy and sensuality, literally embodied in the models he studied so intensively, and Moore’s semi-abstracted helmet heads and upright motives, don’t have much in common.