Christiansborg Castle, Ghana

Christiansborg Castle, also known as Osu Castle, was originally built as a fort by Danish traders in the 1660s on the Gold Coast of West Africa and named for the Danish crown. It later served as the administrative center of the Danish Gold Coast before passing through British colonial control and eventually becoming the seat of government of independent Ghana, a role it held for several decades. Unlike most entries in this group, it was constructed and repeatedly expanded as a fortified coastal trading structure rather than as a purely residential palace, reflecting its origin in the European trade forts built along the West African coast.