This paper reports the synthesis of highly luminescent colloidal nanoplates (NPLs) of perovskite cesium lead halide, with quantum yields up to 84%. The NPLs are synthesized through a modified nanocrystal synthesis method and can be self-assembled into stacked columnar structures or oriented thin-sheet structures. The NPLs exhibit broad emission ranges, high quantum yields, and ease of self-assembly, making them ideal for optoelectronic studies and future device applications. The NPLs are composed of cesium lead halide (CsPbX3) with X being bromide, iodide, or chloride. The emission spectra cover the entire visible spectrum, and the NPLs can be tuned by anion exchange. The NPLs show quantum size effects and can self-assemble into hierarchical structures. The study also demonstrates the self-assembly of NPLs into two different hierarchical structures: stacked columnar phases and large 2D sheets. The NPLs are characterized by TEM, XRD, and SAXS, showing their 2D geometry and crystal structure. The study highlights the potential of perovskite NPLs for optoelectronic applications due to their high luminescence and unique properties. The research was supported by the U.S. Department of Energy.This paper reports the synthesis of highly luminescent colloidal nanoplates (NPLs) of perovskite cesium lead halide, with quantum yields up to 84%. The NPLs are synthesized through a modified nanocrystal synthesis method and can be self-assembled into stacked columnar structures or oriented thin-sheet structures. The NPLs exhibit broad emission ranges, high quantum yields, and ease of self-assembly, making them ideal for optoelectronic studies and future device applications. The NPLs are composed of cesium lead halide (CsPbX3) with X being bromide, iodide, or chloride. The emission spectra cover the entire visible spectrum, and the NPLs can be tuned by anion exchange. The NPLs show quantum size effects and can self-assemble into hierarchical structures. The study also demonstrates the self-assembly of NPLs into two different hierarchical structures: stacked columnar phases and large 2D sheets. The NPLs are characterized by TEM, XRD, and SAXS, showing their 2D geometry and crystal structure. The study highlights the potential of perovskite NPLs for optoelectronic applications due to their high luminescence and unique properties. The research was supported by the U.S. Department of Energy.