Property developer Steve O'Connor had 55,000-cubic-meters of sandstone carved out of a Cheshire cliffside to build this (mostly) underground mansion, which, despite the friendly-looking green roof, is put squarely in the supervillain lair category by that helipad. Built on the former site of a modest two-story cottage, the 16,000-square-foot home features all the high-tech amenities you'd expect, including keyless doors and "iPod docks in ever room." Now it can be yours, discerning homebuyer, for £4.75M (~$7.3M).
According to a post on CheshireLife, O'Connor was influenced by Art Deco styling, though it's not quite evidenced by the hot pink accent walls. The five bedroom, ten bathroom house also comes with an indoor pool and an outdoor TV area.