Stark though it is, the roof terrace with its low ochre-red wall and washed turquoise abstract seems the nearest thing to a garden among the forbidding cliffs of mass housing that rear up all around. Like bold tendrils of organic life, three young girls appear with jump ropes and show off some individual fancy licks, before switching to a stately coordination mode. Their bright white ropes make squiggles in the air like waved sparklers at night, while wrists and feet maintain a rock-steady beat. The joy of skilled movement, of pure synchrony, illuminates their faces.