Parc des Celestins - Lyon, France
The Parc des Celestins designer's primary issue was how to get light in to a car park which goes so far underground. The central core of the car park is a light well lit from the street above, a vast mirror sits at the base of the well and rotates, reflecting and dispersing the light around the seven levels of the park. There is a periscope on ground level allowing passers-by the opportunity to view the cavernous space below.
Image Source: Graham Miln