A　protein-sized　(ca.　4.2x4.2x3.6nm(3))　non-biologically　derived　molecule　{Nb288O768(OH)(48)(CO3)(12)}　(Nb-288)　containing　up　to　288　niobium　atoms　has　been　obtained,　which　is　by　far　the　largest　and　the　highest　nuclearity　polyoxoniobate　(PONb).　Particularly,　in　terms　of　metal　nuclearity　number,　Nb-288　is　the　second　largest　cluster　so　far　reported　in　classic　polyoxometalate　chemistry　(V,　Mo,　W,　Nb,　and　Ta).　Nb-288　can　be　described　as　a　giant　windmill-like　cluster　aggregate　of　six　nanoscale　high-nuclearity　PONb　units　{Nb47O128(OH)(6)(CO3)(2)}　(Nb-47)　joined　together　by　six　additional　Nb　ions.　Interestingly,　the　47-nuclearity　Nb-47　units　generated　insitu　can　be　isolated　and　bridged　by　copper　complexes　to　form　an　inorganic-organic　hybrid　three-dimensional　PONb　framework,　which　exhibits　effective　catalytic　activity　for　hydrolyzing　nerve　agent　simulant　of　dimethyl　methylphosphonate.　The　unique　Nb-47　cluster　also　provides　a　new　type　of　topology　to　very　limited　family　of　Nb-O　clusters.