Spatial transcriptomic technologies promise to resolve cellular wiring diagrams of tissues in health and disease, but comprehensive mapping of cell types in situ remains a challenge. First, I will present сell2location, a principled Bayesian model that can resolve fine-grained cell types in spatial transcriptomic data and create comprehensive cellular maps of diverse tissues. Second, I will present GBM-space, our new effort to discover tumour tissue architecture in glioblastoma using multi-modal genomics. We discover a striking spatial organisation of GBMs, where malignant cell states regionally segregate and associate with distinct tumour microenvironment cells.