Walking through the streets of Berlin is a visually stimulating experience for those who appreciate street art and graffiti. Berlin has been a crucial center of street art activity for the past two decades, a rich playground for street artists and those enamored with street art's audacious impact on the physicality of the city.

With the launch of Berlin Art Week (September 11-16), Berlin has transformed itself into a slick, 24-hour art-promotion machine, complete with influential art fairs, special gallery and museum exhibitions and non-stop art parties that go all night.

Stroke Urban Art Fair is positioned as the alternative to this week's government-subsidized art fairs, which include money-makers like abc art berlin contemporary, Preview Berlin and the Berliner Liste.

Running from September 13-16, Stroke is the only art fair in continental Europe dedicated primarily to urban art. Occupying two floors of Berlin's expansive Postbahnhof, Stroke presents street art paintings, graffiti, photographs and illustrations from over 30 galleries and artist groups from Berlin and around the world.

Urban vs. street art

The street art fair is a curious concept, an oxymoronic term that contains inherent conflicts. Central to the apprehension of street art and graffiti is the concept of space - specifically an appropriation of outside urban space. Street artwork accosts or entertains people in their everyday lives, catching them by surprise in a setting entirely divorced from the realm of the art gallery.

Stumbling upon great street art by yourself is akin to uncovering a secret, and often the physical character of a building or wall informs the context of a work. Bringing street art inside into a gallery space - or an art fair - would seem to lessen the impact of that viewing experience.

What's more, random changes in street space lend an ephemerality to street artworks that is at odds with the controlled environment of the art show. And street artworks' structural resistance to being sold opposes the commodification of art pieces that art fairs promote.

Marco Schwalbe, who co-founded Stroke with his brother in 2009, told me he doesn't consider these factors a problem. The type of art Stroke is based on can include street art, but is situated under a wider umbrella of the urban contemporary. "When we talk about urban art, the meaning is that our lives are more and more influenced by the way we live in urban cities," he said. "The Internet, new technologies - this is what we call urban. It doesn't necessarily have to do with being outside."

In contrast to other art fairs, Stroke's overriding aim is not merely to sell work at the highest market price, which creates refreshingly different vibe palpable even to the casual observer. Stroke retains the old spirit of Berlin: a celebration of the creative impulse over profit.

'Street art is dead'

For many artists, Berlin is becoming inhospitable to the street art scene. The restructuring of the city that has contributed to the recent closure of the Tacheles art squat and impacted live music venues is also affecting the street art scene.

Schwalbe doesn't mince words: "The street art scene is pretty much dead. It's really hard to get walls here in Berlin for artists - legal walls. There's not so much street art anymore."

While it's difficult to get government funding for street art projects inside, it's just as hard to get legal walls for street art outside. This of course doesn't stop street or graffiti artists from producing work outside illegally. Graffiti is still illegal in Berlin and those caught doing it can be arrested.

Schwalbe bemoans the lack of financial support from the state for street art, despite Berlin's clear international reputation as a European center for the genre. But that's where Stroke comes in with a low-cost - and legal - alternative. At a time when the cost of showing at an art fair can be prohibitive for small galleries, Stroke offers reasonable participation fees and doesn't take a cut of the work sold at the fair, factors that draw under-the-radar Berlin talent.

Chilean streetartist Inti agrees, adding that political connections are necessary if you want to do big projects, like festivals. Nevertheless, Berlin "is still one of the best places."

Yet street art has never been more popular amongst the general population. In 1980s New York, writing on city walls was seen as dirty and dangerous, but these days a large amount of street art is widely appreciated for its skill and cleverness. The phenomenon of Banksy's work selling for millions at auction is just one example of street art's profitability. And this year, Stroke expects to see over 10,000 visitors.

Berlin's identity as a city is going through a process of transformation. As Berlin courts multi-million euro exhibitions for traditional art genres, it remains to be seen whether the new Berlin will prioritize the giving of space to urban contemporary art as well.