Many materials like rocks and sediments but also materials for technological application like fuel cells contain a lot of pores. As transport through these porous materials is often driven by fluid flow it is important to understand how material architecture determines the landscape of flow velocities within such a medium. We find that local partitioning of fluid flow between adjacent pores define the overall flow characteristics of a porous material. Combining experiments and computer simulation with theoretical work supports this new idea. This is in contrast to former models where the flow through a material is controlled by the pore size distribution. Our new understanding may help us in better design of materials for example for fuel cells or filtration techniques.