Hirado Castle — Sea Castle of the Christian Daimyo

Hirado Castle occupies a forested peninsula surrounded on three sides by the Hirado Strait, commanding views of both the strait and the town below. Built in 1718 by the Matsuura clan, the castle replaced an earlier fortress destroyed during the Christian persecution — the Matsuura lords had initially protected Christian missionaries in the 1500s before the Tokugawa ban forced them to reverse policy.

The reconstructed five-story keep (1962) contains a museum documenting Hirado's unique position as the first Japanese port opened to Dutch and Portuguese trade (1550). The castle grounds preserve original stone walls and the Hon-maru palace foundation, while the surrounding forest contains walking trails through 300-year-old pine and camphor trees.