Yamen

Sez the OED:
yamun, yamen ya.mAn. Also -oun, -ên; [Chinese ya tent or pavilion of a general, official residence, office + mun gate.] The office or official residence of a Chinese mandarin; hence, any department of the Chinese public service, as the tsung li yamun or Chinese `foreign office', established in 1860.

1747 Astley's New Gen. Coll. Voy. IV. i. vi. 275 Each Magistrate, great or small, has his Tribunal, or Ya-men.
1827 H. E. Lloyd Timkowski's Trav. iii. I. 111 The tribunal (called the yamoun) is the supreme court of the country of the Kalkas: it has the civil and military jurisdiction, and administers justice: sentence is past according to the printed code of laws.
1858 Merc. Marine Mag. V. 45 He saw pagodas, and yamuns.
1883 Sunday Mag. 632 The yamun or official residence of the country magistrate.
1891 Daily News 28 July 5/1 He..made a run for the official yamen, but was overtaken..and murdered.
1907 Times 30 May 5/2 The intention is to attack every yamên and to exterminate all the officials;