noun
central building; central wing
Refers to the main or central building of a complex, such as a library, museum, or hospital. Often part of a proper name.
図書館の中央館は駅の近くにあります。
The library's central building is near the station.
この博物館は中央館と東館に分かれている。
This museum is divided into the central wing and the east wing.
別館 is an annex or separate building, contrasting with the central/main building.
Compound of 中央 (central) and 館 (building, hall). The exact historical derivation is uncertain, but the word follows a common pattern for naming institutional buildings.