As property prices soar most people consider building up but as history shows some people have chosen to go in the opposite direction.
At first blush, underground living can be seen as claustrophobic but it also has many advantages such as resistance to severe weather, quiet living space, an unobtrusive presence in the surrounding landscape, and a nearly constant interior temperature due to the natural insulating properties of the surrounding earth.
Of course, if there is a flood you don't want to be caught in an underground home.
Historically, underground living has featured in many famous stories such as the hobbit holes of the Shire as described in the stories of J. R. R. Tolkien and The Underground City by Jules Verne.
ALSO SEE: First Paris Skyscraper in 42 Years
It is also the preferred mode of housing for some communities in extreme environments as Italy's Sassi di Matera, Australia's Coober Pedy, Berber caves as those in Matmâta, Tunisia, and even Amundsen-Scott South Pole Station.
Underground living is even being considered for the design of a future base on Mars. With today's technologies you can direct natural light into living spaces with light tubes.
Often, underground living structures are not entirely underground, they can be exposed on one side when built into a hill. This exposure can significantly improve interior lighting, although at the expense of greater exposure to the elements.
Below, we round up a few cool underground houses to show how it can be done.
Earth House Estate Lättenstrasse, Dietikon, Switzerland
These earth covered houses - designed by Peter Vetsch - are grouped around a small artificial lake with the entrance hidden and integrated at the side of the settlement.
There's nine different-sized houses, varying from 3 to 7 bedrooms.
To maximise use of natural light the daytime areas are situated towards the south whereas the bedrooms are towards the north. In the middle, you find the bathrooms and the connecting stairs to the basement, which also has a subterranean parking lot.
Festus Cave Home, Missouri
Once a mine shaft, then a roller rink and concert venue for artists like Ike and Tina Turner. Now it's a 17,000 square-foot home with four bedrooms and two bathrooms.
William Sleeper, the man who built the home, said one of the pluses about living in a cave is heating and cooling costs. It stays an average of 70 degrees year round.
Any dugout, Cooper Pedy, Australia
In the South Australian opal mining town of Cooper Pedy many of the locals have put their mining skills to an alternative use, creating underground homes.
These homes, or "dugouts" let them escape the blazing sun and let's face it, the landscape isn't much to look at anyway. Below we have a couple of typical images from Cooper Pedy dugouts.