In an age of confusing, sprawling art exhibitions, the current Sharjah Biennial stands out as an intelligent, tightly curated show featuring some hard-edged works that ever so slightly unsettle the delicate political and cultural ecosystems in the Gulf.

The star of the Ashcan School was influenced by the Impressionists. Yet for all the surface charm, his work shows a fear of what lies beneath

Scottish painter Craigie Aitchison was dismissed by some critics as twee. But the brightness and warmth in his work give it a compelling edge, as Adrian Hamilton discovers at the first show since the artist's death

“You learn to know where people want to go even if they don’t know themselves,” one tube employee at Bank station told me, as I wandered around the labyrinth of tunnels, escalators, and platforms in search of Mark Wallinger’s own Labyrinth – artwork number 142 out of 270.

In a show of exuberant generosity and breadth, images of natural beauty and brutal destruction jostle with Flickr fun

Mark Wallinger's new commission, 'Labyrinth', aims to subvert London Underground's iconography and disorient the viewer

A theatrical showman of a composer presided over a weak ending which couldn't transcend its own experimentalism

Few highlights struggle through a soupy, samey, set in Hackney

The rave reviews and whispers on 'the new Warhorse' are well-placed

Public galleries make much of their artist commissions these days. The more traditional their collections, the more directors want to give a contemporary zing to their establishments by presenting a new work by a contemporary artist. But they are, by nature constrictive. You ask an artist to make a statement about the collection, the edifice or whatever, but too often it remains just that: a statement rooted to a place by the terms of the deal.

Hundreds of tiny etchings create his vast portraits, but does knowing the process help us know Chuck Close? This fine show may fill in the gaps

Some great regional galleries have very special collections indeed and are overlooked at our peril. The Whitworth in Manchester, for example, has a textiles holding second only to the V&A's in London, and is also strong on wallpaper, landscape painting, and drawings both historic and contemporary. A few months from now, it will close for a major refurbishment which, when complete, will see the galleries dramatically open out to the park at its back. How to mark this transitional moment?

Chuck Close suffered a spinal aneuryism in 1988, and the story of the making of his large-scale, painted portraits, works often composed of lozenges of colour organised inside grid-like patterns which cohere visually the further you recede from them, often goes hand in hand with a general acknowledgement of his tremendous battle against physical adversity. He's the man who is forever fighting to make it new from the maddening confines of a wheelchair.

Antoni Tàpies was recovering from a lung infection in a mountain sanatorium during his late teens when he began reading the fiction and philosophy that would shape his later oeuvre. The year was 1942.

Although R B Kitaj lived in Britain for nearly 40 years, he ended up an obsessive, wounded outsider.