This is the 7219th most frequent Korean word.
중국대사관은
"Chinese Embassy."
Here, '중국대사관은' is the subject of the sentence, referring to the Chinese Embassy.
중국대사관은 서울에 위치해 있습니다.
The Chinese Embassy is located in Seoul.
In this case, '중국대사관은' acts as the object of necessity construed with the verb '방문해야 한다', meaning the action is directed at the Chinese Embassy.
나는 중국대사관은 방문해야 한다고 생각합니다.
I think I should visit the Chinese Embassy.
Here, '중국대사관은' is the acting agent performing the implementation in the sentence.