Amalgamated maps, comprising interior maps overlaid on venues indicated in general maps can be automatically generated. Initially, interior maps can be obtained through targeted network searches, whose search results can be filtered to retain those that are most likely useable interior maps. A bounding polygon is generated for both interior map and venue exterior from general map. Subsequently, directional histograms representing orientations of lines in bounding polygons are generated and compared to automatically identify a rotation to align the interior map with the venue exterior from the general map. Anchor points are identified to locally deform the interior map, preserving internal structures, to better align with the venue exterior. Once aligned, the interior map can be combined with the general map, forming an amalgamated map. Updated geocoding can be performed based on locations of establishments in the venue as indicated by the interior map.