10 Most Expensive Houses 3. Villa Leopolda By Ghani Khan Estimated Value: $500–$750 Million Villa Leopolda stands as a majestic testament to French opulence, history, and prestige along the glamorous French Riviera in Villefranche-sur-Mer, France. Originally purchased by King Leopold II of Belgium in 1902 as a gift for his mistress, this extraordinary residence was later transformed by American architect Ogden Codman Jr. in the 1930s into its current form a grand Neo-Palladian mansion with a rich blend of classical European design and lavish details.