1. One or more computer-readable storage devices having stored thereon computer-executable instructions for generating a digital map comprising map tiles and independently provided tiles of map details, the computer-executable instructions directed to steps comprising: obtaining a map context indicating a geographic region and a zoom level; detecting a custom mechanism for providing the tiles of map details in response to the map context; utilizing the map context to determine identifiers for the map tiles; providing the map context to the custom mechanism; receiving, in response to the providing, the tiles of map details and associated identifiers, wherein each associated identifier uniquely identifies only a single one of the tiles of map details; matching the tiles of map details to corresponding map tiles based upon the determined identifiers for the map tiles and the associated identifiers that are associated with the tiles of map details, with each matched tile of map details and corresponding map tile pair representing an equivalent geographic area; and causing at least some of the matched tiles of map details to be displayed superimposed over at least some of the corresponding map tiles.