Goryokaku star fort

Japan's first Western-style fortress, finished in 1864 as a five-pointed star designed to deny attackers a blind spot. Five years later it was the last stronghold of the short-lived Republic of Ezo, and the site of the final battle of the Boshin War. The tower exists because the shape only reads from above.

In the winter of 1868 a defeated navy sailed north, occupied a European-style fortress, and held what may have been the first election in Japanese history. Then they lost, and with them went the samurai era.

Japan’s first Western-style fortress is a five-pointed star of moats and ramparts, built in 1866 to repel foreign navies — then used instead by the shogunate’s last loyalists, who declared a doomed republic here before the empire’s army ended the samurai age on these lawns in 1869. The pentagon only reveals itself from the tower next door: 107 meters up, the star snaps into geometry.

In late April the moats become one of Japan’s great hanami spectacles — 1,600 cherry trees tracing the star in pink. The rest of the year it is a calm park with a magnificent secret shape and a reconstructed magistrate’s office at its heart.