Sled dogs in Svalbard, Norway live in little houses built a foot or two off the ground so they remain accessible even after snowstorm. Raising the floor above the cold ground also keeps the dogs warmer in the winter.
The Titlis Cliff Walk in the Swiss Alps took five months to build and is thought to be Europe's highest suspension bridge, at a stomach-turning 9,800ft (3,000m) above sea level.
Tree houses, treehouses, or tree forts, are platforms or buildings constructed around, next to or among the trunk or branches of one or more mature trees while above ground level. Tree houses can be used for recreation, work space, habitation, observation or as temporary retreats.
The sign above the door of restaurant and hotel “Am Paulusbogen” is partially submerged in the flooded centre of the Bavarian town of Passau, about 200 km (124 miles) north-east of Munich June 3, 2013. (Photo by Michaela Rehle/Reuters)
People enjoy skating at the open air Christmas ice rink on the first floor of the Eiffel Tower after its reopening on December 19, 2016 in Paris The ice rink of about 200 square metres and on the first floor of the tower (57 metres above the ground) is open to the public until February 19, 2017. (Photo by Joel Saget/AFP Photo)
The ruins of a castle stand above the town of Rocca Calascio, close to Santo Stefano di Sessanio in the province of L'Aquila in Abruzzo, inside the national park of the Gran Sasso e Monti della Laga, Italy, September 7, 2016. (Photo by Siegfried Modola/Reuters)
A sauna building sits above the clouds at 9,280 feet (2,752 meters) at the Rifugio Lagazuoi in the Dolomite Mountains near Cortina d' Ampezzo in northern Italy July 17, 2015. The Dolomites are home to the Dolomiti Bellunesi National Park and were declared a UNESCO World Heritage Site in August, 2009. (Photo by Bob Strong/Reuters)