Incredible, impenetrable homes

Transforming concrete compound

Once the 50-foot retractable concrete wall shutters are closed, the drawbridge — yes, a drawbridge — and the 20-foot metal roll-down gate close off the glass anterior of the home. This concrete cube can ride out almost any scenario you throw at it.

As far as owners who value their security above all else, this home is the gold standard of privacy and protection.

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The Creech House

Whitefish, Mont.

Many mountain cabins provide breathtaking views and easy access to the slopes. But for some devoted ski aficionados, that's not enough.

With its elaborate electronic-control features and a high-tech security system, the home makes up for what it lacks in concrete walls in its digital "fortress" features.

On-site and smartphone-accessible security features can control home operations such as a full view of the exterior, a detailed alarm system, remote contact system for police and fire departments, and window-lock checks. Add to that being able to keep tabs on the activity in most rooms.

"It's a nice little feature to see your what your kids are doing," owner Kay Creech says. And with 16 rooms, seven bedrooms — with the ability to sleep 34, if necessary — 10 bathrooms and four decks with views of Glacier National Park, any tool to help you keep track of the kids is essential. The home is on the market for $16 million.

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The Penthouse

London

Few sights are as impressive as those provided by One Hyde Park apartments. In particular, The Penthouse, known as the most expensive apartment in the world, provides an unparalleled two-floor perch above the city. It also boasts an array of security features that would seem only natural for anyone owning this one-of-a-kind property.

Sold last April for $221 million, the penthouse condo is rumored to have been purchased by a Ukrainian owner who prefers to protect his identity. Former police officers patrol the premises, all of the glass is bulletproof  — in case of a helicopter assault, perhaps — an air purifier protects against gas attacks and a panic room is available, should all else fail.

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Malator House

Pembrokeshire, Wales

Like a chameleon peeking out from beneath the grass, the Malator — or the "Teletubby House," as it’s known colloquially because of its striking similarity to the home featured in the famous British children's TV show — blends almost seamlessly into the lush green hills surrounding its perch over St. Brides Bay in Wales.

Most of the home is underground. It features an earthen roof that perfectly emulates the hills around it. The glass front facesthe bay — the only hint that a home is hidden somewhere below. Like a Hobbit hole of contemporary experimental architecture, the Malator was designed and built in 1998 by avant-garde architectural firm Future Systems, now known as Amanda Levete Architects after a company split in 2008.

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Safe House

Los Angeles

An elaborate home in the Hollywood Hills with a spectacular view of Los Angeles inspires the kind of envy and awe that leaves you speechless. Like something out of a spy movie, the home includes two panic rooms and five floors of smart-technology controls accessible from anywhere in the world.

"We designed a new, architecturally based security system," says Al V. Corbi, the architect and home-security expert who built and lives in the house.

Even the door is protection-savvy. It can screen visitors and make decisions about entry, says Corbi, who runs a security company called Safe. "It can't take a bribe, it can't fall asleep and it’s always there."

• Video: Smartphones pretty savvy when it comes to home security

• Bing: Learn more about fortress homes

• MSN Money: Insurance for zombie attacks?

Safe House

Adding extra security, support beams burrow deep under the home.

"If the whole hillside fell away, the house would look like one of those oil rigs on stilts," Corbi says, "but it would remain standing."

As a last resort in an emergency, the home has a helipad on the roof. Corbi has a contract with a local helicopter company that will help his family escape if the mountain roads are cut off by damage, fire or smoke.

For what is arguably the safest home in America, Corbi is asking $7.25 million.

See more fortress homes on Forbes.com.

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Star Castle

Hugh Town, Isles Of Scilly, England

The Isles of Scilly, off the Cornish Peninsula, are a beloved summer destination for Brits. One of the island's most important sights on the small island of St. Mary's can be yours for a night or 14.

Star Castle is the only entry on our list that is more than just a second home for the attentive owner, Robert Francis. It's an honest-to-goodness, eight-pointed, mini-castle hotel, complete with a moat — now dried up —a proper set of castle tunnels, a bell tower, old cannons, battlements and a dungeon, should your credit card be declined.

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The 'Fortress Home'

Los Angeles

Located on a ridge high up in the Hollywood Hills, a steel-and-concrete sanctuary sits blocked off from the road behind it and is essentially inaccessible from every other direction.

The home features views of the Los Angeles sprawl beneath it — an especially inspiring view at night, when the city becomes a string of electric pearls. An elaborate security system includes cameras in almost every corner of the property, a key-access system on nearly every door and a gate that requires owners to carry their card with them or risk sleeping on the sofa. All of it, of course, can be remotely accessed by smartphone.

City regulations have since banned the construction of such homes, so the property, listed for $11.9 million, is a rare find.

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Subterra Castle

Shawnee County, Kansas

Security-conscious owners can spend inordinate amounts of money making their homes more like a fortress. But few homes can approach the impregnability of Kansas resident Ed Peden's repurposed nuclear-missile silo.

What the government paid $4 million to build, Peden bought for a steal at $40,000 in 1982. Along with his wife, Dianna, Peden spent decades fixing up the abandoned and flooded silo he first toured in a small boat.

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Subterra Castle

The Pedens have made the main part of their home in the old control room and filled it with bongo tables, exotic lights, and fabric draped beneath the ceiling and on the walls.

"I'm really kind of a peacenik from the '60s," says Ed Peden, whose hippie sensibilities partly inspired him to turn a facility created for mass destruction into a soft and comfortable home that smells of patchouli and incense.

See more fortress homes on Forbes.com.

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Chateau Artisan

Redland, Fla.

Charles Sieger, half of the Miami architectural firm Sieger Suarez, made a name by designing and building creative high-rise residential and commercial buildings. But when it came to designing his own home, Sieger instead drew his inspiration from French and British chateaus, medieval castles and manor houses.

He dug out a giant circular moat — a time-tested invasion deterrent — to surround the $10.9 million home. He also built one road leading in and out of the home, put up a heavy metal gate, and installed regular and infrared cameras along the road and around the house.

"In particular, I bought the property because it was on the side of a canal, which also provides protection," Sieger says.

• Video: Smartphones pretty savvy when it comes to home security

• Bing: Learn more about fortress homes

• MSN Money: Insurance for zombie attacks?

The Pierre Rock House

San Juan Islands, Washington

Literally nestled in the rocks near the shore of one of Washington state's San Juan Islands, the Pierre — French for stone — was inspired by owner Merrill White's desire to live atop a stone outcropping.

Architect Tom Kundig of the Olson Kundig architectural firm went one better, and rather than seating the home about a rock outcropping, he cut into the rock itself to create a stone seat overlooking the sea.

• On our blog, 'Listed': 'Safe at home' becoming a popular design addition

Slide show:  Hidden rooms: What's the big secret?

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The Pierre Rock House

Depending on your point of view, the home may disappear into the landscape. Much of what is visible is the imposing concrete that juts out above ground.

• Video: Chinese pensioner builds fortress to avoid eviction

• What are homes worth near you?

• On our blog, 'Listed': $1 billion house uninhabitable?

The Pierre Rock House

Fitting for a part of the country known for its devotion to "green" practices, the home's floor is created from crushed pieces of the rock that was excavated, and the roof holds a lush lawn system that collects and recycles water.

See more fortress homes on Forbes.com.

• Video: Behind the walls of the Tower of London

• MSN Money: Home safety: Hidden risks to kids

• On our blog, 'Listed': Zombie-proof condos are sold out