American Kivas or European Ringforts

The Ancestral Puebloans (Anasazi) People and the Celtic and Gaelic people of Europe both built ringforts of stone masonry. 

European Ringforts

Ringforts, ring forts or ring fortresses are circular fortified settlements that were mostly built during the Bronze age up to about the year 1000. They are found in Northern Europe, especially in Ireland. There are also many in South Wales and in Cornwall, where they are called rounds. Ringforts come in many sizes and may be made of stone or earth. Earthen ringforts would have been marked by a circular rampart (a bank and ditch), often with a stake wall.

Sources:

https://en.wikipedia.org/wiki/Ringfort

Caherconnell Stone Fort, Co. Clare, Ireland  https://youtu.be/TiqfaRMoGX0

Ireland http://www.abandonedireland.com/Cahergall_1.html

Ireland Ringfort https://commons.wikimedia.org/wiki/Category:Grianan_of_Aileach

https://en.wikipedia.org/wiki/Grianan_of_Aileach

https://en.wikipedia.org/wiki/Kiva

http://www.americansouthwest.net/new_mexico/chaco_culture/casa-rinconada-kiva-wall_l.html

https://en.wikipedia.org/wiki/Lowry_Pueblo

https://en.wikipedia.org/wiki/Aztec_Ruins_National_Monument

Sweden https://en.wikipedia.org/wiki/Eketorp

Sweden https://youtu.be/ij_MOWbk9eY