Prince Yuri I Dolgoruki (Russian: Юрий Долгорукий, "Yuri the Long-arm"), also known as George I of Rus', (c. 1099–15 May 1157) was the founder of Moscow and a key figure in the transition of political power from Kiev to Vladimir-Suzdal following the death of his elder brother Mstislav the Great. He reigned as Velikiy Kniaz (Grand Prince) of Kiev from September 1149 to April 1151 and then again from March 1155 to May 1157.
Yuri was the sixth son of Vladimir Monomakh. Although his birthdate is uncertain, some chronicles report that Yuri's elder brother, Viacheslav, said to him: "I am much older than you; I was already bearded when you were born." Since Viacheslav was born in 1083, this pushes Yuri's birth to c. 1099/1100.
In 1108, Yuri was sent by his father to govern in his name the vast Rostov-Suzdal province in the north-east of Kievan Rus'. In 1121, he quarrelled with the boyars of Rostov and moved the capital of his lands from that city to Suzdal. As the area was sparsely populated, Yuriy founded many fortresses there. He established the towns of Ksniatin in 1134, Pereslavl-Zalesski and Yuriev-Polski in 1152, and Dmitrov in 1154. The establishment of Tver, Kostroma, and Vologda is also popularly assigned to Yuri.