Multicellular microbial communities in suspension and on surfaces are ubiquitous from the laboratory to the ocean, and yet the nature and dynamics of those populations are still not well understood. Their biomechanical properties have a large impact on human life - from controlling sepsis, to wastewater management, to biofuel production. While there are macro-scale, descriptive models, our current understanding of how multi-cellular colonies form, grow, fragment, and disseminate is still in its infancy. Motivated by this biological phenomena, the research in our group has focused on developing and validating mathematical models for the biomechanics of bacterial biofilms on surfaces and aggregates in suspension. We will discuss our aggregate fragmentation model as well as the macroscale impact on population-level dyanmics. We will also discuss our biofilm model which is based on an extension to the immersed boundary method for heterogeneous rheologies. In both cases, we use high-resolution microscopy images of biofilms and aggregates to initialize the positions of each bacteria. Our main results reveal the strong effect spatial heterogeneity has on the biomechanical properties and demonstrate that properties estimated by the model agree quantitatively with experimental data. Time permitting, we will also present our investigation into the statistical properties of the positions of bacteria in a biofilm. We present a methodology for computationally generating artificial biofilms which are quantitatively consistent with the rheology of experimental data. Furthermore, statistical properties of the positions of bacteria are found to have a significant, and sometimes counter-intuitive, effects on the mechanical properties of the biofilm.