Powerfull Graffiti in Black and White

Sam3 is a graffiti artist from Murcia, Spain. He's not exactly your average graffiti artist. His paintings are in black and white mostly, but stunningly powerful nonetheless. This is the power of color (yes, that includes black and white) to transform architecture.
This painting is in Tudela, Spain:
This one in Porto, Portugal:

Check out his website and Flickr page.