Below is the strangest skyscraper proposal you will ever see, an upside down underground tower block lit by a giant mirror.From deflecting the suns rays with mirrors to light up an entire Austrian town which is shrouded in shadow to fiber optic channels which light underground caverns, combinations of heliostats (sun trackers) and light pipes are being increasing used to create architectural lighting effects which are entirely natural.Included here are a variety of technique, including the recent park heliostats, in New York and light pipes which channel daylight from street level to the subway in Berlin. Vote for your faves.