Abstract The brain shows a highly specific structural organization, also in its connectivity. How may genetic specification or epigenetic self-organization influence the layout of cortical systems networks? We developed a computational model of spatial network growth to investigate the conditions leading to similar network density and clustering as found in the cortical connectivity of cat and macaque monkey. An essential factor in the model was the introduction of spatial borders. We further compared metric aspects of wiring in the macaque brain and the simulated networks, which suggest that cortical networks may trade perfect minimal wiring length for shorter average shortest paths among cortical areas.