Douglas is the capital and largest town of the Isle of Man, situated on the east coast at the mouth of the River Dhoo. Originally a secondary port behind Castletown, it grew in importance through the eighteenth-century trade and became the seat of government when the capital was transferred in 1869. Beneath its streets, extensive underground warehouses were constructed during the smuggling era to store dutiable goods destined for clandestine export to Britain and Ireland.