6. Rancho San Carlos in California has been owned by the same family for over 100 years, and it's easy to see why. Sitting on 237 acres, the 30-room main residence spans almost 30,000 square feet on two natural terraces, and features unique design details that correspond to the house's rich history.
Price: $125 million
Additional perks include 10 guest cottages, extensive equestrian facilities, and sprawling orchards.