Taken on and off the market throughout the last several years, this modern-day fortress is a perfect example of the billionaire bunker trend. Located in the Hollywood Hills, the gated property sits on its own private hilltop. Besides the gorgeous views, the nearly 8,000-square-foot home blends luxury with advanced security systems. Designed by Al V. Corbi, founder of the security solutions firm SAFE (Strategically Armored and Fortified Environments), the home features two panic rooms and a system of interlocking special doors that can seal off certain bedrooms from the rest of the home. You'll notice that though the house is extremely secure, it's elegantly designed and not necessarily what you'd expect from a fortified fortress.