By incorporation of NO3- ligands with trigonal planar geometry as surface modifiers into the lanthanide cluster core backbone to remarkably improve the dimension of cluster cores, two novel lanthanide cluster compounds, Dy30I(mu(3)-OH)(24)(mu(3)-O)(6)(NO3)(9)(IN)(41)(OH)(3)(H2O)(38) (1) and Dy104I4(mu(3)-OH)(80)(mu(3)-O)(24)(NO3)(36)(IN)(125)(OH)(19)(H2O)(167) (2) (HIN = isonicotinic acid), have been obtained under hydrothermal conditions. Single-crystal X-ray diffraction shows that in both cluster compounds, the block blocks of [Dy-26(mu(3)-OH)(20)(mu(3)-O)(6)(NO3)(9)I](36+), {Dy-26}, are the largest cage-shaped lanthanide cluster cores known. Compound 1 is the first tetramer based on the linkage of two different types of high-nuclearity lanthanide clusters and IN ligands, while compound 2 represents the first tetramer constructed by {Dy-26} clusters and IN linkers.