The colours of this artwork are truly stunning, with triangles and rectangles providing an abstract form of a city scene.

This brightness has helped this artwork to become amongst the most reproduced of all Klee artworks, alongside the likes of Angelus Novus and Twittering Machine.

Burg und Sonne was the original title of this piece, which translates directly as Castle and Sun, capturing the main focal points of this painting.

Some have occasionally mis-interpreted the sun as in fact a moon, but the title of the painting clarifies that.

Klee himself produced several of these intricate tiled scenes and they have proven to be amongst the most loved by his fans.

The aspect of this painting that makes it so popular as a print reproduction is the way in which whilst abstract, individual elements of the city are still easily recognisable, making it more accessible than some other artworks from his career.

Whilst conforming to abstraction, it could be argued that Castle and Sun fits into any or all of Expressionism, Cubism and Surrealism. Whilst some will present Dali's Burning Giraffe or Picasso's Les Demoiselles d'Avignon, it is the colour that truely gives Castle and Sun it's independance.

The creation of form through an abstract formation of geometric shapes reminds us more of the work of Wassily Kandinsky and other members of the Bauhaus movement.

Klee was known to have aligned himself with the Bauhaus artists in the early 20th century so any similarities are to be expected. It was Klee's colour palette that was to help him retain his artistic independence.

Color possesses me. I don’t have to pursue it. It will possess me always, I know it. That is the meaning of this happy hour: color and I are one. I am a painter.

It was after a 1914 trip to Tunisia that Klee was permanently set upon a style of abstraction, when previously he had merely dabbled from time to time.

The simplicity of abstract art is it's beauty, but also the reason for why it was dismissed so passionately early on. The likes of Paul Klee would find their work derided by traditionalists.

Today, of course, Castle and Sun and others of that ilk are respected for the qualities that they have introduced into the art world.

The Paul Klee Notebooks were a collection of writings and research made by Klee around his obsession for colour. This particular painting outlines how colour would play a crucial role in his work.

Similar paintings to Castle and Sun include Fire in the Evening, Ancient Harmony, New Harmony and Flora on Sand which all follow the artist's tiled abstract technique from that part of his career.