Abstract. -In this Letter we investigate networks that have been optimized to realize a trade-off between enhanced synchronization and cost of wire to connect the nodes in space. Analyzing the evolved arrangement of nodes in space and their corresponding network topology a class of small world networks characterized by spatial and network modularity is found. More precisely, for low cost of wire optimal configurations are characterized by a division of nodes into two spatial groups with maximum distance from each other, whereas network modularity is low. For high cost of wire, the nodes organize into several distinct groups in space that correspond to network modules connected on a ring. In between, spatially and relationally modular small world networks are found.Introduction. -Synchronization phenomena occur in a diverse range of contexts in nature, engineering and society: cardiac pacemaker cells, neurons in the brain, fireflies that flash in unison, the power grid or consensus formation among people are just a few example applications from these fields. All of these are distributed systems embedded in space in which most couplings are local, but often also non-local long range couplings are present. Hence, most of these systems can be described as small world (SW) networks [1]: nodes represent elementary units of the system such as neurons, fireflies, power stations or people and links in the network represent interactions that describe how the elementary units influence each other. Synchronization phenomena on SW and other complex networks have found much attention in the recent literature, see, e.g. [2], for a review. Moreover, in the system of coupled oscillators which we consider below, superior synchronization is essentially related to maximizing the second smallest eigenvalue of the graph Laplacian. This eigenvalue -the algebraic connectivity-is an important invariant for undirected graphs and is, e.g., relevant for the analysis of the robustness of networks against node removal or for epidemic spreading [3].