A family seat, or simply a seat, was the principal manor of a medieval lord, which was normally an elegant country mansion and usually denoted that the family held political and economic influences in the area. In some cases, the family seat was a manor house. Dynasty names were sometimes derived from the name of a family seat. An example of this would be the House of Windsor, the royal family of the United Kingdom and the Commonwealth realms.
Badge of the House of Windsor (1938-1952) 
This term was first used in the 11th century throughout the text of the Domesday Book
, where it was rendered as the Latin word caput,
which literally means "head" or "top". The term continues to be used throughout the British Isles today.
A Clan seat
refers to the seat
of the chief of a Scottish clan