Marugame-jo is one of Shikoku's four original castles and the smallest surviving castle tower in Japan. The three-storey keep was completed in 1660 under the Kyogoku clan and has remained standing — unburned, undemolished, unrestored — ever since, which puts it in rare company. The castle is listed as a National Treasure.
What makes Marugame Castle distinctive even by Japanese standards is the stone walls, or ishigaki, that rise below the keep. Built in stages between 1597 and 1643, they climb in a progressively steeper fan curve — the nori-dan construction style — that looks almost impossible from below. The walls are up to 60 metres high and visible from much of the city. Cherry trees planted on the terraces between the walls turn the approach into one of Kagawa Prefecture's most popular blossom sites in April. The castle hill is a 10-minute walk southeast of Marugame Station.