Cell division in the vast majority of bacteria is driven by the synthesis of new cell wall peptidoglycan and is catalysed by the divisome. Central to the divisome is the peptidoglycan-synthesising protein complex FtsWI, which is regulated by the heterotrimer FtsQBL. I will present the cryo-EM structure of the activated divisome catalytic core complex FtsWIQBL from Pseudomonas aeruginosa at 3.7 Å resolution. The structure reveals details of the periplasmic interfaces within FtsWIQBL, including the positioning of FtsI by the coiled coil of FtsBL, as well as a transmembrane domain containing FtsWIBL, but not FtsQ. I will provide molecular mechanisms of a multitude of cell division phenotypes of several mutations and reveal a large conformational switch between presumably inactive and active states of the FtsWI core enzymes. Furthermore, our work on FtsA revelaed antiparallel double filaments that we suggest play a role in divisome activation on the inside of the cell, utilising the intrinsic curvature of FtsA filaments to align divisome activity with the cell's curvature - a "rudder" function that has previously been suggested for MreB filaments in the elongasome. Finally, I will discuss organisms that use FtsZ for cell division, but do not have a cell wall or divisomes. In those, cell wall synthesis cannot be the driver of cell division and initial experiments towards understanding cell division without divisomes will be presented.