Saratov was founded in the 16th century as a fortress to protect southern districts of the Russian Empire. Later on it became the heart of one of the largest Russian provinces, and also a city of merchants, gold miners and first Russian manufacturers. In the 19th century Saratov became a major commercial center, especially after the railway to Moscow was built in the 1870s. The modern city has become a large industrial complex that sprawls for many miles along the river. The city’s 2.8-km / 1.7-mi highway bridge across the Volga opened in 1965 is one of the longest river bridges of the kind in Europe. Saratov’s varied and large-scale industries are headed by the production of heavy equipment and chemicals. Petroleum and natural gas occur in the locality and thus contribute to Saratov’s chemical plants, which produce synthetic alcohol, synthetic fibers, acetone, and ammonium sulfate. All through the 16th and up to the 19th century local population of the entire area was also formed by Cossacks, Tatars, Orthodox fringe groups (as opposed to church reforms), German colonists and even the captured Frenchmen that once were the soldiers of Napoleon. Yuri Gagarin, the first man in space, began his career in Saratov and did his first air flight there.