1. A computer-implemented method in a network server for enabling quick transitions to indoor map data from a base map displaying outdoor map data, the method comprising: receiving, by one or more processors from the client device, a request for map data for a specified geographic area and a specified zoom level; retrieving, by one or more processors, outdoor map data for the requested geographic area at the zoom level, wherein the outdoor map data including a plurality of features corresponding corresponds to externally-visible physical entities; determining, by one or more processors, that the outdoor map data includes a map feature corresponding to a multi-floor building; determining, by one or more processors, a default floor for the multi-floor building; generating, by one or more processors, a single map tile including (i) descriptions of geometry for the plurality of features and (ii) metadata including an overview of available indoor map data for the feature corresponding to the multi-floor building, the overview including one or more of an indication of the default floor, an indication of a number of floors for the multi-floor building, a description of a bounding box for one or more floors of the multi-floor building, and names for each floor of the multi-floor building; and providing the map tile to the client device in response to the request, for rendering a base map of the specified geographic area and generating, using the metadata, a widget for activating a display of a selected floor, wherein determining the default floor includes selecting a floor other than a ground floor of the multi-floor building based on whether the default floor is likely to be interesting to a user.