金城汤池 (金城湯池) jīn chéng tāng chí

jīn chéng tāng chí set phrase metal city walls surrounded by a moat of boiling water; an impenetrable fortress
Domain: Idiom 成语 , Subdomain: , Concept:
Notes: (Guoyu '金城湯池'; Mathews 1931 '金城湯池', p. 49)