This hilltop castle was ruled mostly by the Matsudaira clan from the 1660s and played a part in the Shimabara Rebellion. It was rebuilt in 1964. As well as lotus ponds, tangled gardens, almost 4km of massive stone walls overgrown with greenery, and staff dressed in period costume, the castle grounds house four museums. Most notable is the main castle, displaying arms, armour and items relating to local Christian history, with English explanations.
Also within the castle compound is Seib艒 Kinenkan, dedicated to the work of native son Kitamura Seib艒, sculptor of the Nagasaki Peace Statue.
From February to August, several times a month during the nighttime Yoru no Jin program, the castle exterior is lit up and visitors wander inside with torches (flashlights) to view the exhibits (admission 楼720).