18-19 Kensignton Palace Garden

The garden at 18-19 Kensington Palace is owned by billionaire steel magnate Lakshmi Mittal and is located in London's affluent Billionaire's Row. Mittal walks the same streets as the world's wealthiest and most famous people. Mittal shares a paper route with Prince William and Kate Middleton. Lakshmi Mittal is the chairman and CEO of ArcelorMittal, the world's largest steel producer.

His house has 12 bedrooms, Turkish baths, an indoor pool, and a parking space for 20 cars. This most expensive home is located in Billionaire's Row, which is London's most affluent neighborhood, and is not far from Mittal's. Sir Charles Barry designed his house in 1845.

These homes are incredible architectural feats, designed and owned by extraordinary people, and they truly put the "home" in "home sweet home."

Owned by Lakshmi Mittal.

Location: London, U.K.

Price: $128 million