Xanadu 2.0, Bill Gates' $130 Million Mansion, Tracks Residents. 

Bill Gates is among those who have held the label "world's richest man" the longest.  

His twelve-figure net worth was propelled by the digital behemoth Microsoft Corp., 

which the billionaire established. As one might expect from someone who founded one of the most ,

successful software companies in history, he constructed his own home from the ground up.

You are given a key when you enter the house that is preprogrammed ,

with your preferences for everything from lighting and music to room temperature. 

The key keeps track of your movements, and as a safety precaution, 

if you are on the floor and no key is found, you will activate the alarm system.