During cell division, eukaryote chromosomes transform between a somewhat open interphase and somewhat closed metaphase conformation. I will discuss our group’s work on studies of the mechanics of both these states of the genome.  I aim to discuss the role (and underlying mechanism) of SMC complexes in the folding, compaction, and topological organization of metaphase chromosomes, and also to describe how epigenetic marks appear to play a key role in controlling nuclear mechanics and topology.