Abstract: Existing human genome assemblies have almost entirely excluded highly repetitive sequences within and near centromeres, limiting our understanding of their organization, evolution, and essential role in chromosome segregation. Now, the first complete, telomere-to-telomere human genome assembly (T2T-CHM13) has enabled us to deeply characterize peri/centromeric repeats at single-base resolution, totaling 6.2% of the genome (189.9 Mb). Mapping the inner kinetochore protein CENP-A revealed overlap with the most recently duplicated subregions within centromeric repeat arrays. A comparison of chromosome X centromeres across a diverse panel of individuals illuminated high degrees of structural, epigenetic, and sequence variation. In total, we present an atlas of human centromeres to guide future studies of their complex and critical functions as well as their evolutionary dynamics.