Many years ago Brighton had a problem with tagging (the defacing of walls and other streetwise surfaces with spraycan "signatures") and graffiti art. And spent a lot of time and money painting out the offending scribbles. But in time the City Council came to distinguish between vandalism of tagging and art of graffiti and decided to encourage the latter, whilst continuing to paint out the former. And so today the city has an internaional reputation for the quality of its graffiti art which the city's tourist department even promotes as a visitor attraction. Areas were graffiti art could be practised were identified. Some of these were permanent - the walls of buildings; others less so, such as hoardings around building sites
By its nature graffiti art is ephemeral. The surfaces of walls deteriorate and hoardings around building sites are eventually removed when the building is complete. Other designated sites have their art work replaced after some time has elapsed, such as the Urban Art Wall in the New England Quarter which changes each July during the Hip Hop Festival.
In addition, many businesses have had their premisses painted in the style of graffiti art. You can come across it in many areas of the city, but there are high concentrations in the North Laine, in the streets to the west of the London Road shopping centre (Providence Place, Elder Place), and out at Black Rock.
The weblinks below provide more information and more examples of graffiti art in Brighton.