Baku Metro
Baku Metro is a rapid transit system serving Baku , the capital of Azerbaijan . 
<triplet> Baku Metro <subj> rapid transit <obj> instance of <subj> Baku <obj> located in the administrative territorial entity <subj> Azerbaijan <obj> country <triplet> Baku <subj> Azerbaijan <obj> capital of <triplet> Azerbaijan <subj> Baku <obj> capital