/COLONIZATION MECHANISM _AFFORDANCES __________________________ what NON VISIBLE CITYURBAN DENSITY __________________________ how big 55×33 Km __________________________ why MATERIALIZE THE INVISIBLE __________________________ where ATHENS, GREECE __________________________ process 01.100X500m GRID02.BUILT TO UNBUILT RATIO ON GRID __________________________ what NON VISIBLE CITYURBAN DENSITY __________________________ how big 55×33 Km __________________________ why MATERIALIZE THE INVISIBLE __________________________ where ATHENS, GREECE __________________________ process 01.100X500m GRID02.BUILT TO UNBUILT RATIO ON GRID