The Barbican Centre, London, 4 March – 31 May
The Barbican keeps its hand in when it comes to contemporary art by commissioning regular installations in its Curve Gallery space. The latest artist to be given the space is Swiss-born Roman Signer, known for his humourously scientific ‘action sculptures’ in which everyday objects are catapulted, exploded or otherwise transformed/propelled/destroyed to exacting guidelines that he sets. Signer plans to turn the Curve into a canal by navigating a kayak through the long space.

Marlborough Fine Art, London, 4 March – 17 April
Ken Kiff RA, who passed away in 2001, is the subject of a new show at Mayfair’s Marlborough Fine Art. The Academician produced haunting but human paintings and prints that harked to fantasy and myth. Although Kiff’s semi-figurative images unwind threads of mysticism that stretch back to William Blake and beyond, their free and original forms are as fresh as ever. His work is ripe for rediscovery.

Fourth Plinth, Trafalgar Square
This Thursday there will be a new visitor in Trafalgar Square among the tourists: a skeletal sculpture of a horse by the German-American artist Hans Haacke. Gift Horse (2015) is the latest work to take pride of place on the square’s Fourth Plinth, which has become the site of the city’s most prestigious rotating public art commission. Haacke used an etching by horse painter George Stubbs RA as source material for this satirical take on equestrian sculpture (and for your information, the RA Collection has a superb collection of Stubbs’ anatomical drawings).

Strawberry Hill House, London, from 1 March
Horace Walpole – the 18th-century Man of Letters and friend to many of the RA’s founding Members – will be happy in his grave this week, as his extraordinary Strawberry Hill home is reopened to the public after careful restoration. The mini, medieval-esque castle by the Thames (turrets, stained glass and gargoyles galore) was a Gothic revival building before the Gothic revival, and was the place where Walpole wrote the highly influential The Castle of Otranto (1764), considered the first Gothic novel.

Transition Gallery, 28 Feb – 29 March
Cathie Pilkington RA and Mike Nelson RA are among the 50 artists who contribute erotic or fetish objects to the show Sex Shop. Previously on view in Folkestone and now at Transition Gallery in Hackney (although wouldn’t it have been better for it to be staged in Soho?), the responses to the ‘Sex Shop’ range from sculptures that feature naked body parts to artworks that appear like bondage gear, all the while referencing how desire can be merchandised.

Sam Phillips (@SamP_London) is Editor of RA Magazine.