Who owns the most expensive house in the world? Where is the most expensive house in the United States? What amenities, from garages that can hold double-digit numbers of cars to regulation-size basketball courts and multiple swimming pools, are considered standard these days for the most expensive mansions in the world?

Treehouses are platforms or buildings built into a tree. They are constructed around, next to, or in mature trees. They are usually above ground level. Tree houses can be used for recreation, work space or as an observation deck. A tree house can be a peaceful quiet place for seclusion or solitude.