Think of the nucleus as the command center of the mammalian cell. How does a cell manage the constant flow of cargo moving in and out of its nucleus without traffic jam? Every second, thousands of molecules race through nuclear pores, tiny 50-60 nm “high-security gates” of the nucleus. This system keeps cells alive but is easily disrupted by stress, neurodegeneration, and viruses like HIV-1, Dengue, Zika, and SARS-CoV-2. In this talk, I’ll introduce cutting edge 3D super-resolution microscopy and single-particle tracking tools-PALM, STORM, and next-generation 3D MINFLUX to visualize rapid cellular dynamics. We will take a tour into the nanoscale 3D-world of nucleocytoplasmic transport, where we catch a glimpse of individual cargoes zipping through single, transport-active nuclear pore in real time. By revealing this hidden traffic, we uncover how cells function and what happens when their gates fail.