Aleysk — the city (since 1939) in Altai Krai of Russia. The administrative center of the Aleysk district of Altai Krai which part isn't. The city of Aleysk forms the city district.
By the order of the Government of the Russian Federation in 2014 it is included in number of monotowns in which there are risks of deterioration in economic and social situation. The city is located on east suburb of Ob Plateau, on the left river bank Aley (the left inflow of Ob) at a river Goryovki confluence, in 125 km to the southwest from Barnaul on federal Highway A322 Barnaul — Rubtsovsk — border with Kazakhstan. Through the city also there passes the line of West Siberian Railway Barnaul — Rubtsovsk — Semipalatinsk.
Lands on river banks Aley have departed to Russia in the 17th century. In 1913 to the northwest from the village of Malopanyushevo (nowadays within the city) the settlement at the railway Aleysk station has been founded on the Turkestano-Sibirsky railroad under construction (Novonikolayevsk — Semipalatinsk). In 1926 — 1938 — the settlement of city type Aleysk. In January, 1939 by the Decree of Presidium of the Supreme Council of RSFSR the settlement has been given the status of the city. Growth of Aleysk was promoted by development of the food and overworking industries.Climate — continental. Average temperature of January −17,6 °C, July of +20,3 °C.