Considering the shogunate's desire to isolate the foreigners, the spot was ideal: it was hemmed in by rivers to the east and west, by the Saigoku-kaido Road to the north, and by the sea to the south.
東西を川に、北を西国街道、南を海に囲まれた土地で、外国人を隔離するという幕府の目的に適う地勢であった。