Lüshunkou District (also Lyushunkou District; ) is a district of Dalian, Liaoning province, China. Also formerly called Lüshun City () or literally Lüshun Port (), it was formerly known as both Port Arthur (Порт-Артур ) and Ryojun (旅順). The district's area is and its permanent population is 324,773.
Lüshunkou is located at the extreme southern tip of the Liaodong Peninsula. It has an excellent natural harbor, the possession and control of which became a casus belli of the Russo-Japanese War (1904–05). Japanese and then Russian administration was established in 1895 and continued until 1905 when control was ceded to Japan. During that period, it was world-famous and was more significant than the other port on the peninsula, Dalian proper.
In English-language diplomatic, news, and historical writings, it was known as Port Arthur after a British Royal Navy Lieutenant named William Arthur who surveyed the harbor in the gunboat HMS Algerine in 1860. At that time Lüshun was an unfortified fishing village.
During the period when the Japanese Empire controlled and administered the Liaodong (formerly Liaotung) Peninsula it was called 旅順, the Japanese pronunciation of the Chinese characters in the city's name. After the Japanese defeat in World War II, the city was under the administration of the Soviet Union, which rented the port from China, until 1950. Although the Soviets presented the port to the new People's Republic of China in 1950, Soviet Armed Forces troops remained in the city until 1955.
Central Dalian is some farther up the coast, sprawling around the narrowest neck of the Liaodong Peninsula (), whereas Lüshun occupies its southern tip. (See Landsat Map below Zoomed – Lüshun City surrounds the lake-like structure clearly visible near the peninsular tip—the lake-like feature is the inner natural harbour of the port, a very well-sheltered and fortifiable harbour to 19th century eyes.)
The Liaodong Peninsula is located northwest in relation to Korea, the Yellow Sea to its southeast, the Korea Bay to its due east, and the Bohai Sea (or Gulf) to its west.