The Ambani family's Mumbai tower, Antilia, cost $1 billion to build. Check out the world's most expensive private residence.

• The family of Anant Ambani, who just had a massive pre-wedding party, has built a tower in Mumbai. 
• The 27-story house, called Antilia, is said to be the most expensive private residence in the world.
• Antilia's interiors have rarely been photographed, but it has a 50-seat cinema and three helipads.

Mukesh Ambani, India's richest man, and his family live in a fittingly opulent 27-story tower on Mumbai's most exclusive street.