Seat of government is a term commonly used to refer to the structure that houses the nexus of an interstellar nation's government, though it can also refer to that nation's capital city or planet. The term can also be used to apply to political subdivisions of a nation. Well-known seats of government in local space include:
The Palais de la Concorde in Paris, Earth. (United Federation of Planets.)
The Great Hall in the First City, Qo'noS. (Klingon Empire.)
The Hall of State in Ki Baratan, Romulus. (Romulan Star Empire.)
The temporary offices of Castellan Alon Gehmor's government in Cardassia City, Cardassia. (Cardassian Union.)
The Tower of Commerce in the Sacred Marketplace, Ferenginar. (Ferengi Alliance.)
The Deelatava in Keelee-Kee, Tezwa. (Republic of Tezwa.)
The Senate Tower in Leran Manev, Trill. (Trill Republic, UFP.)
The Chamber of Ministers Building in Ashalla, Bajor. (Republic of Bajor, UFP.)
The Parliament Andoria Complex in Laibok, Andor. (Andorian Empire, UFP.)
The Presidential Palace of the Enochians, on Enoch VII.
The Presidential Palace of the Trevans, on Treva.