Teepees are a style of tents made by native Americans. They were usually made from wooden poles, wrapped in decorated animal skins.
A tree house is a kind of cubby house (or Wendyhouse) that is built up a tree. Treehouses are usually just big enough for two or three children.
A vault is a structure made from intersecting arches, or many parallel arches, to make a large space out of a compressive material like stone or brick.
With many vaulted spaces being built underground, a vault also became known as a place to store treasure, and today a bank vault is a locked box inside a bank where you can store valuables.
