"We can take that ugly gray wall and transform it into something that's beautiful," co-designer Ray Mawst said.

Pieces of the Wall, well and thoroughly graffitied, are scattered around the city, preserved in both prominent plazas and hidden corners.

Some art museums overawe with the sweep of their collections. Others thrill with a few perfectly placed masterworks. The best of them embody their cities’ ambitions and fulfill an ideal ...