Tamagusuku Castle, Gusuku fortress in Nanjō, Japan

Tamagusuku Castle is a limestone fortress perched on a hilltop at 180 meters elevation near Nanjō in Okinawa Prefecture. The fortification includes multiple stone enclosures connected by wooden stairs and natural stone walls that form part of the structure itself.

According to the Chūzan Seikan, Tamagusuku Castle was built by Amamikyu, the Ryukyuan creation goddess, making it the oldest castle on Okinawa Island. King Tamagusuku, fourth king of the Eiso lineage (1260–1349), is said to have resided here and expanded the fortress. Its stone walls suggest construction around 600 years ago. It was designated a National Historic Site in 1987.

The main bailey holds the Amatsugi Amatsugi Utaki, one of the seven sacred sites of the Ryukyuan creation myth, and pilgrims on the Agariumai circuit stopped here. The gate is cut from a single natural rock, and the small size of the enclosure suggests the site served worship more than warfare.

The site has parking spaces for roughly ten vehicles and offers free access to visitors. Wooden stairs lead to the fortress enclosures, so wear sturdy footwear when exploring the grounds.

The main bailey's walls survive almost intact, and its gate is cut straight through a single natural rock rather than built from blocks. The second and third baileys lost their stone walls after World War II, when the nearby Camp Chinen supply area was run under US Army cover and the masonry was taken away as building material.