Tsar Peter I of Russia, also known as Peter the Great, ruled from 1682 until his death in 1725. He is best known for modernizing Russia and transforming it into a major European power. Peter implemented extensive reforms in government, military, and culture, introducing Western technologies and ideas. One of his significant achievements was the founding of Saint Petersburg in 1703, which became the new capital of Russia. Peter's reign also included the Great Northern War, which expanded Russian territory and influence. His efforts laid the groundwork for Russia's emergence as a formidable nation in the 18th century.