While climbing onto the first rung of the property ladder is a tricky task for the average homebuyer, for billionaires, a sprawling mansion with an eight-figure price tag is a mere drop in the ocean – but what $50 million (£35.4m) can buy you around the world might just come as a surprise. From plush penthouse apartments in space-starved cities to 800-acre estates in the wilderness and ornate French palaces, click or scroll through and let's take a tour of some of the world's most expensive homes...