Genomic architecture appears to play crucial roles in health and a variety of diseases. How nuclear structures reorganize over different timescales is elusive, partly because the tools needed to probe and perturb them are not as advanced as needed by the field. To fill this gap, the National Institutes of Health Common Fund started a program in 2015, called the 4D Nucleome (4DN), with the goal of developing and ultimately applying technologies to interrogate the structure and function of nuclear organization in space and time. In this perspective, Roy et al. share the progress of the NIH Common Fund 4D Nucleome program, which aims to map the structure and function of genomic architecture in space and time by developing necessary tools and techniques and delivering these resources for the wider scientific community. [ABSTRACT FROM AUTHOR]