Lastly, When reviewing the concentrations of Graffiti across all three areas, they all appeared to be heavily concentrated in Alley type conditions. 

Downtown's Cultural District while spare with Graffiti, accumulated their's within alleyways.
In the Strip District, while a wealth of Graffiti blankets the neighborhood, the vast majority encircles the Major Shopping blocks of 21st - 23rd Street, along Penn Avenue. The Graffiti concentrates in Alleys and building sides and backs, as well as side streets.
and on Shadyside's Ellsworth Corridor, Graffiti accumulates on the backs of Garage structures as well as Stairwell infrastructure.