Berlin

Berlin is synonymous with street art, and for some historic examples, head to the East Side Gallery, a 1.3-km section of the Berlin Wall that’s covered with 105 paintings by artists from all over the world. Originally painted in 1990, a year after the Wall came down, some have since been restored.

Athens         

In the Greek capital, graffiti has taken a political tone since the start of the financial downturn and, more recently, the refugree crisis. Alternative Athens offers street art tours (€30pp) that take in everything from stencils and tags to vast murals, in the Gazi, Monastiraki, Psirri and Thiseio neighbourhoods.

Valparaíso

Street art took off in Valparaíso, Chile, in the late Sixties and early Seventies, when students painted murals as a statement that art should be available to all. Many works were removed under the Auguste Pinochet’s dictatorship, but today the city is colourful once agin. Valpo Street Art Tour will take you (for free) to the Museo de Cielo Abierto (The Museum of Open Sky), a concentration of streets where every wall tells a story.

Bristol

You’ll find street art festivals all around the world, and the biggest in Europe is Upfest, which takes place each summer in Bristol, home of Banksy. This year saw more than 300 artists from around the world painting walls around the Bedminster and Southville areas. Some of the works are on temporary surfaces, while others remain on venues and buildings for the whole year until the next event.

Melbourne

Australia’s most artsy city is home to an impressive array of murals and graffiti; the city’s tourist board has even put together a map to help you track down some colourful examples. Building owners can give permission for artists to decorate their buildings, with some of the best works concentrated around the laneways, such as Hosier Lane.

http://www.independent.co.uk/travel/news-and-advice/best-street-art-in-the-world-cities-berlin-wall-bristol-upfest-valparaiso-chile-athens-melbourne-a7366181.html

Antonis Kourtidis, a Greek who found a way to "convert" malignant tumor cells to benign cells National and Kapodistrian University of Athens won the World Final of the Manfred Lachs Space Law Moot Court Competition