Tsugaru Tamenobu began designing Hirosaki Castle in 1603, but died leaving its completion to his son, Nobuhira. Full-scale construction began in 1610, and within a year, the tenshu, eight yagura watchtowers and gates had been completed. The speed of construction was due to the recycling and relocating of former castle structures from elsewhere. Currently, the main tenshu, three watchtowers and five castle gates still exist, and all are designated Important Cultural Properties, making this one of the most historically valuable castle sites. Because of bulges appearing in the eastern stone walls beneath the tenshu, the tower was lifted and transported 70m across the Honmaru main bailey in 2015, and an investigation and restoration work on the ishigaki commenced. The restoration work is expected to take ten years, after which the tower will be returned to its original position.