Astro, who’s infamous energy and originality make him one of the world’s major street artists, has completed a monumental outdoor mural for a public art initiative in the Portuguese city of Loures.  Presiding over a busy street, the front-facing façade of the residential building has been totally transformed into a mesmerising optical illusion that penetrates into a deep and dark abyss. astro-optical-illusion-wall-loures-arte-publica-lisbon-designboom-02-1 Paris-based artist Astro honed his craft with his first graffiti piece in 2000 and since then he has been a main protagonist in transforming the fortunes of street art from a ‘degraded’ art form into its very own cultural movement. Since the turn of the century, and more specifically in recent years, graffiti has been noticed as a noble art form and it so rightly should as the principles of true art is not to portray, but to evoke. astro-optical-illusion-wall-loures-arte-publica-lisbon-designboom-05 The spontaneity and impulsive imprint of graffiti is displayed through Astro’s latest mural as he mixes curves, calligraphy and dynamic shapes into a play of shadows and colour. Various layers of blue pigment are orientated to appear as if a tunnel was running through an ordinary apartment block. When viewed from the street, the piece for the Loures Arte Publica Project transports visitors into another dimension – placing them in the heart of a mysterious and perplexing realm. And that, is the very reason why public art, and particularly graffiti, should never be underestimated. Take a closer look at the project in the image gallery and be sure to follow Astro on Instagram, @astro_odv_cbs, for daily updates