Nagoya Castle, Japanese castle ruins in Karatsu, Japan

The remains occupy several hilltops on the Hatonosaki Peninsula in Saga Prefecture, showing stone walls, foundations, and traces of moats. The complex covers around 17 hectares and features multiple levels connected by stairways and pathways between the rises.

Toyotomi Hideyoshi ordered the castle built in 1591 as a base for the invasion of Korea, and it was finished by March 1592 after about eight months of rushed work, second in scale only to Osaka Castle. After Hideyoshi's death in 1598 the troops withdrew and the castle lost its role. Terazawa Hirokata dismantled it from 1602 to build Karatsu Castle, and after the Shimabara Rebellion the shogunate had key stone walls broken down.

Hideyoshi chose this site partly because the place name Nagoya sounded the same as his birthplace, Nago-no, and the hill was called Katsuoyama, an auspicious name. Around the castle some 120 barracks sites housed the assembled daimyo; 118 camp sites are confirmed today, 65 with surviving remains. In the tea room of the Yamazato enclosure Hideyoshi held tea gatherings and a costume party in a melon field.

The ruins spread across the hill of Hato Cape, about 90 metres high, with the main enclosure, secondary enclosures and the Tenshu platform on different levels reached by paths and stone steps. The adjacent Saga Prefectural Nagoya Castle Museum stands next to the site. A tablet-based virtual reconstruction lets visitors view the castle as it appeared while walking the grounds.

The castle's name was written 名古屋 in Meiji-era prefectural maps, the same characters as the city of Nagoya; the spelling 名護屋 was only standardised around the Taisho era. A 1592 audience here with Toyotomi Hideyoshi was held by the Dominican friar Juan Cobo, sent as envoy of the Philippine governor.