A National Important Preservation District of Historic Buildings, the Kasashima District flourished as the base of the Shiwaku naval forces and merchant shippers during the Edo period (1603-1867). Enclosed by mountains on three sides and a fine natural harbor to the north, the district is crisscrossed by narrow alleys and two wider streets, Toshoji running north-south and Machodori running east-west along the harbor. Many residential buildings along the streets have latticed bay windows and clerestory “insect cage” lattices, legacies of the celebrated Shiwaku carpentry tradition.