Cave Dwellings
A cave dwelling is a special "structure", a useful space formed not by addition, but by subtraction, i.e., Subtracting certain things in nature .The Loess plateau is prevalent in the northwest and its neighboring regions, with the depth of the loess extending from 1oo to 200 meters. With little seepage and a very strong vertical nature, this provides a very good precondition for the development of cave dwellings. At the same time, the natural condition of dry weather, little rain, cold winter and limited timber also creates an opportunity for the development and continuity of cave dwellings which are warm in winter, cool in summer, very economical and require no timber in construction.
There are three kinds-cliff, ground and hoop cave dwellings.
The cliff cave dwelling is an earth cave dug horizontally along the vertical earth cliff. Each cave is about 3-4 meters wide and 5-9 meters deep. The straight wall is about 2-3 meters high. The top of the cave is dug into a semi-circular or slotted barrel arch. The various caves can lead to each other through tunnels between them. It is also possible to add another cave upon the cave, and the upper and lower caves can be linked to each other through a passage.
The ground cave dwelling is a square or rectangular pit dug Out of the level ground to form a ground yard. Then, a cave is dug horizontally on various walls of the pit, which is used mostly in sections lacking a natural precipice. A person standing on the level ground can only see the treetops of the ground yard and cannot see the houses.
A hoop cave dwelling is not a real cave, but only a cave-shaped house put up with brick or adobe on the level ground modeled after a cave dwelling. The hoop cave dwelling can be a single storey, it can also be a building. If the upper storey is also a hoop dwelling, it is called a "dwelling upon a dwelling". If the upper storey is a wooden structured house, it is called a "dwelling upon a house".

                西北窑洞民居
窑洞是一种特殊的"建筑"，不是用"加法"而是以"减法"即"减"去自然界的某些东西而形成的合用的空间。流行在西北及其邻近地区的黄土高原。深达一二百米、极难渗水、直立性很强的黄土，为窑洞提供了很好的发展前提。同时，气候干燥少雨、冬季寒冷、木材较少等自然状况，也为冬暖夏凉、十分经济、不需木材的窑洞，创造了发展和延续的契机。
窑洞有崖窑、地窑和箍窑三种。
崖窑即沿直立土崖横向挖掘的土洞，每洞宽约3-4米，深5-9米，直壁高度约2米余至3米余，窑顶掘成半圆或长圆的筒拱。并列各窑可由窑间隧洞相通。也可窑上加窑，上下窑之间内部可掘出阶道相连。
地窑是在平地掘出方形或矩形地坑，形成地院，再在地坑各壁横向掘窑，多用在缺少天然崖壁的地段。人在平地，只能看见地院树梢，不见房屋。
箍窑不是真正的窑洞，是以砖或土坯在平地仿窑洞形状箍砌的洞形房屋。箍窑可为单层，也可建成为楼。若上层也是箍窑即称"窑上窑"；若上层是木结构房屋则称"窑上房"。