World Trade Center elevator. Massively fast: the floor indicator lights fly past. Yet this one is unusual, seldom-used; near the ground floors it moves horizontally, until it leaves the building like a subway train, narrow-gauge, pivoting with great suppleness around 200-degree u-bends as if it were a great mechanical snake, traveling through cobblestone streets between European-style village houses. This track is seldom-used: a lady has left boxes before her door, which the train encounters and simply pushes along. Ahead is an obstacle: a fence with heavy posts like wooden storage cabinets; the train must rise vertically to overcome them.