Georg Baselitz: one of the world's greatest living artists

As a curator and an amateur obsessed with art, for whom all art of all ages is intrinsically contemporary, but who has now for almost half a century been trying to follow contemporary art of now, the work of Georg Baselitz has for me been a constant measure. Each person interested in art needs to find such a person.

For me, Baselitz has been an artist and a friend who ever since I came across his work has never disappointed, who constantly surprises, and who, in a career of now more than half a century too, has to my way of seeing always found it possible to reinvent himself.

London is fortunate in that it is about to host a veritable festival – not a retrospective exhibition – of Baselitz's work that will embrace three manifestations, each of which, in their own way, will demonstrate both the singularity and complexity of his achievements. And he is only 75 years old.

At the large Gagosian Gallery space in Britannia Street, near King's Cross station, there opens on 13 February some 15 spectacular inverted self-portraits under the title Farewell Bill. Bill is Willem de Kooning, the great figurative Abstract Expressionist.

Figurative abstract itself sounds like a contradiction: it is a contradiction that has been an essential leitmotif of Baselitz's own work over his entire career, in which he has found endlessly rich variations – this exhibition is but the latest joyous iteration. Full of spontaneous graphic drawing and sensual colour, each painting on white ground, which I was privileged to see in the artist's studio two months ago, is an iconic souvenir of witty self-observation.

A little earlier, on Thursday, the British Museum will show a group of some 90 works on paper in an exhibition titled Germany Divided: Baselitz and His Generation. Baselitz was one of a number of artists who hailed from Saxony (then of course part of the German Democratic Republic, the "wrong side" of post- Second World War-divided Germany), most of whom came to West Germany before the wall was erected in 1961.

His generation included Gerhard Richter, Markus Lüpertz – who is also exhibiting in London soon at the Michael Werner Gallery in London's Mayfair – Sigmar Polke and Blinky Palermo. Now all these artists are regarded, both in Germany and worldwide, as classics, but I can remember well at the time of an exhibition I helped organise at the Royal Academy in 1981 (A New Spirit in Painting) when the then director of the National Gallery in Berlin told me in the friendliest possible way that Baselitz was not even an artist.

The legendary William Rubin, then director of the Museum of Modern Art, New York painting department, whose measure of contemporaneity lay in the work of Frank Stella, expressed his bafflement that I could find space in my head for Baselitz and these other artists, all of whom, with the exception of Palermo, were included in the RA show. It was the first time any of them had received exposure outside the larger German-speaking world, where, even at the time, they were reviled outside a small insider circle.

The third manifestation, opening at the Royal Academy on 15 March, is an exhibition of 16th-century Italian Mannerist chiaruscuro woodcut prints from the artist's own collection. Baselitz discovered this world as a student in Italy in the early 1960s when these objects were relatively easy to find. Now they are priceless and rare beyond measure. Baselitz has twice built up probably the finest collection of such prints in the world – to rival any great museum, including the Albertina in Vienna where they have just been shown.

He started collecting as a young man and, to the best of my knowledge, the selling of his first collection allowed him to buy the legendary medieval castle of Derneburg near Hanover, which for many years, since the congress of Vienna, had been in British hands. Abandoned after the Second World War it then served as the artist's studio for several decades until he recently moved to a house near Munich to be closer to his family.

These prints by and after artists of the late Renaissance, such as Correggio and Parmigianino, inspired an extraordinary print series by the artist he made back in the 1960s called A New Type. These were representations of defeated German soldiers using this almost forgotten technique of printing that suggests form, volume and depth, and are positively painterly in themselves. They are among Baselitz's greatest works.

Germany Divided: Baselitz and His Generation, British Museum, London WC1 (020 7323 8299) Thursday to 31 August. Georg Baselitz: Farewell Bill, Gagosian Gallery, Britannia Street, London WC1 (020 7841 9960) 13 February to 29 March. Renaissance Impressions: Chiaroscuro Woodcuts from the Collections of Georg Baselitz and the Albertina, Vienna, Royal Academy of Arts, London W1 (020 7300 8000) 15 March to 8 June

Norman Rosenthal curated a major retrospective of the artist's work at the Royal Academy of Arts in London in 2007