How can I merge overlapping polygons (same shapefile) in ArcGIS 10.3 without losing polygon area, i.e. the total area of the new, merged polygon should equal the area of all individual polygons combined.
The individual polygons I want to merge are different parts of the same city - Berlin pre-WWII. I want to calculate the area of the city at that time. The city is spread over several old map sheets, which I had to georectify before digitising the city boundaries as polygons. Because of the age of the maps, the map sheets slightly overlap after being georectified, which means that the individual polygons that make up the city overlap as well. How can I merge these polygons into one polygon of the whole city without losing area?