Mesa Verde

 

Cliff Palace, Ancestral Puebloan, 450–1300 C.E., sandstone, Mesa Verde National Park, Colorado (photo: Steven Zucker, CC: BY-NC-SA 2.0)

    Starting around 1000-1100 C.E., large living structures were built within the sides of cliffs or even above some of the cliffs and are located in the Mesa Verde National Park in Colorado. There are around 600 structures that were built during this time period. The people who built these dwellings are known as the Ancestral Puebloans or also known as the Anasazi. Pictured above is the largest known cliff dwelling out of all of them and is called the Cliff Palace. This area has about 150 rooms and over 20 big circular rooms. All of these buildings ranged from one to four stories high and some even touched the ceiling of the cliff. Each building was constructed of bricks made of a mixture of clay, sand, straw, and sticks. They also built large circular rooms known as Kivas that were often designed for ceremonial purposes as well as just a regular living space. Normally they are topped with a roof made of wood and all the empty space around these Kivas were considered a plaza. There isn't an actual known reason to why they built these cliff dwelling just educated guesses. After around 1300 C.E., this area was actually left abandoned which is also unknown to why. Drought and lack of resources is the main assumption of why they were abandoned. 

Kiva without a roof, Cliff Palace, Mesa Verde National Park (photo: Adam Lederer, CC: BY-NC-SA 2.0)

https://smarthistory.org/mesa-verde-cliff-dwellings/