Only　rarely　have　polyoxometalates　been　found　to　form　core-shell　nanoclusters.　Here,　we　succeeded　in　isolating　a　series　of　rare　giant　and　all-inorganic　core-shell　cobalt　polyoxoniobates　(Co-PONbs)　with　diverse　shapes,　nuclearities　and　original　topologies,　including　50-nuclearity　{Co12Nb38O132},　54-nuclearity　{Co20Nb34O128},　62-nuclearity　{Co26Nb36O140}　and　87-nuclearity　{Co33Nb54O188}.　They　are　the　largest　Co-PONbs　and　also　the　polyoxometalates　containing　the　greatest　number　of　Co　ions　and　the　largest　cobalt　clusters　known　thus　far.　These　molecular　Co-PONbs　have　intriguing　and　atomically　precise　core-shell　architectures　comprising　unique　cobalt　oxide　cores　and　niobate　oxide　shells.　In　particular,　the　encapsulated　cobalt　oxide　cores　with　different　nuclearities　have　identical　compositions,　structures　and　mixed-valence　Co3+/Co2+　states　as　the　different　sized　Co-O　moieties　of　the　bulk　cubic-spinel　Co3O4,　suggesting　that　they　can　serve　as　various　molecular　models　of　the　cubic-spinel　Co3O4.　The　successful　construction　of　the　series　of　the　Co-PONbs　reveals　a　feasible　and　versatile　synthetic　method　for　making　rare　core-shell　heterometallic　PONbs.　Further,　these　new-type　core-shell　bimetal　species　are　promising　cluster　molecular　catalysts　for　visible-light-driven　CO2　reduction.