#4 – 18-19 Kensington Palace Gardens, London
Lakshmi Mittal, an Indian industrialist, didn’t find a problem with spending $220 million on a home, which was at the time of the purchase the priciest house in the world. This property can be found on a street called Kensington Palace Gardens, otherwise known as Billionaires Row. The marble used to decorate this house was taken from the same quarry that supplied the Taj Mahal.