1. A method for displaying a map on a client device having a given display capability, the method comprising: storing map data on a server, the map data comprising a plurality of layers, each layer comprising vector information delineating features in the map belonging to a respective feature category; defining a set of templates on the server responsively to the display capability of the client device, each such template being associated with a respective one of the layers and indicating a visual characteristic of the features in the layer with which the template is associated; downloading to the client device from the server at least a subset of the templates; downloading to the client device from the server the vector information in a portion of one or more of the layers of the map data corresponding to a selected area of the map; and rendering on the client device, based on the downloaded vector information, an image of the selected area of the map in accordance with the visual characteristic indicated by the downloaded templates.