In September 2016 geophysical surveys were conducted at Korshamn, as one of the main harbour bays of the island of Bjorko, situated outside the town boundaries of the Viking town of Birka. The investigation of a solitarily raised plateau at Erik Steffanssons hemland revealed the outline of a large Vendel-period house. Together with further anomalies at a one-sided terrace at Kalvhagen a whole manor complex might be seizable predating the Viking-Age settlement activities on the island. The latter dwelling is superimposed by a major Viking-Age hall connecting to a fenced special area as known from e.g. Lejre and Tisso and linked to cult activities. Both the structures and the chronological depth correlate well with the ancestral property of Birka's royal bailiff Herigar as mentioned in Rimbert's Vita Anskarii. If this assumption is correct even the whereabouts of Scandinavia's first church should be located in the immediate vicinity. The consequences of this identification cannot be overestimated: In terms of the emergence of the Viking town, its royal administration and the earliest Christian mission in Scandinavia.