JMSDF Sasebo Museum "Sail Tower" (Former Sasebo Naval Arsenal Site)

The JMSDF Sasebo Museum "Sail Tower" (海上自衛隊佐世保史料館セイルタワー) is a seven-story naval heritage museum and public relations facility operated by the Japan Maritime Self-Defense Force (JMSDF) in Sasebo City, Nagasaki Prefecture. The museum chronicles the full arc of Japanese naval history at Sasebo — from the Meiji-era establishment of the Sasebo Naval District in 1889 through the Imperial Japanese Navy's wartime peak to the modern JMSDF.

The building itself is an artifact of naval history. The lower two floors incorporate the restored structure of the Sasebo Suikosha (佐世保水交社), a three-story Western-style officers' club originally built in 1898 (Meiji 31) to serve as a social and lodging facility for Imperial Navy officers, a reception venue for foreign naval officers, and a banquet hall with a grand dining room. The octagonal decorative roof and herringbone stonework on the Kokusai-dori (International Street) side preserve the original Meiji-era architectural character. After Japan's surrender, Allied occupation forces requisitioned the Suikosha as an officers' club; it was returned to Japanese control in 1982 (Showa 57).

The new seven-story structure was built around and above the restored Suikosha, with its glass facade representing a vast blue sea and its distinctive rooftop panels shaped like white sails — earning it the "Sail Tower" nickname. The museum opened at this location on March 10, 1997, succeeding an earlier Self-Defense Force Defense Materials Museum (自衛隊資料館) that had been established in 1968 at the Sasebo Supply Facility.

Visitors ride an elevator to the 7th floor observation deck and descend through the exhibitions: Floor 7 features panoramic harbor views and JMSDF promotional films; Floor 6 covers the period from the Nagasaki Naval Training Institute (長崎海軍伝習所) to the establishment of Sasebo Naval District in 1889; Floor 5 documents the Sino-Japanese War (1894–95) and Russo-Japanese War (1904–05); Floor 4 focuses on the Pacific War, including the Sasebo Naval Arsenal's role as one of four principal Imperial Navy shipyards that employed some 50,000 workers at peak wartime capacity, constructing and refitting destroyers, light cruisers, submarines, and other warships — and serving as a repair facility for the battleships Yamato and Musashi; Floor 3 covers JMSDF ship history and operations; Floor 2 displays modern JMSDF equipment and activities; and Floor 1 hosts rotating special exhibitions and a museum shop.

The Sasebo Naval Arsenal (佐世保海軍工廠), whose legacy the museum preserves, was established in 1903 (originally a ship repair facility from 1889, expanded to "Sasebo Shipyards" by 1897). In 1913, a 250-ton crane was installed enabling construction of large warships. During World War II, the arsenal was one of Japan's four principal naval shipyards. After the war, U.S. Marines of the 5th Marine Division landed at Sasebo on September 22, 1945; United States Fleet Activities Sasebo was formally established in June 1946 on part of the former arsenal grounds, while the remainder became Sasebo Heavy Industries.

Today the museum holds approximately 4,400 items in its collection, of which about 1,300 are on permanent display. These include ship models, navigational instruments, uniforms, weaponry, wartime photographs, and documents tracing Sasebo's evolution from a quiet fishing village into one of Japan's premier naval bases. The museum is recognized as a component of the Japan Heritage site "Chinzufu Yokosuka, Kure, Sasebo, Maizuru — Towns where you can experience the dynamism of modern Japan." Admission is free.