We introduce a routing solution called landmark overlays for urban vehicular routing environments (LOUVRE), an approach that efficiently builds a landmark overlay network on top of an urban topology. We define urban junctions as overlay nodes and create an overlay link if and only if the traffic density of the underlying network guarantees the multihop vehicular routing between the two overlay nodes. LOUVRE contains a distributed traffic density estimation scheme that is used to evaluate the existence of an overlay link. Then, efficient routing is performed on the overlay network, guaranteeing a correct delivery of each packet. We evaluate LOUVRE against the benchmark routing protocols of greedy perimeter stateless routing (GPSR) and greedy perimeter coordinator routing (GPCR) and show that LOUVRE performs higher in packet delivery and achieves lower hop count.