"Welcome to West Oakland" is an iconic sign by GATS on top of a building at Martin Luther King, Jr. Way and 25th Street in Hoover Foster/Ghosttown. The sign has been there since at least 2009.  

The front and 25th street side of the building was painted with the "Ants" mural by Daz, Desi W.O.M.E, Dave K of Community Rejuvenation Project

ants portion photo CC BY-NC-ND 2.0 by Dave Schumaker

ants mural portion. photo CC BY-NC-ND 2.0 by 
William Newton

ants mural portion. photo CC BY-NC-ND 2.0 by 
William Newton


photo CC BY-NC 2.0 by Perry Willett
photo CC BY-NC 2.0 by Perry Willett

2013 view of the both sides, kind of in between murals. photo CC BY-NC-SA 2.0  W. W. Watson

Here is a picture of the building with a different mural on the right side (2011). This is a picture of the side that doesn't face the street (2010). The amazing Jessica Hess has painted this building.
This is what the building looked like before the mural (2009).

non-street side. not by CRP. photo CC BY-NC-SA 2.0 by blarfiejandro