at the centre of the area was the shops , as the locals could only bring themselves to call it : a large square building , the bottom layer of which were storefronts , and above these two further floors windowless from the front and which displayed instead murals of the sort designed by left-leaning community visionaries in the seventies and eighties here a diverse mix of smiling faces ; beside it a huge tree acting as metaphor for simultaneously the roots of history and the branches of society .