Kaluga is a city and the administrative center of Kaluga Oblast, Russia, located on the Oka River  southwest of Moscow. Population:

Kaluga was founded in the mid-14th century as a border fortress on the southwestern borders of the Grand Duchy of Moscow. It was first mentioned in chronicles in the 14th century as Koluga; the name is from Old Russian kaluga 'bog, quagmire.' In the Middle Ages, Kaluga was a minor settlement owned by the Princes Vorotynsky. The ancestral home of these princes is located southwest from the modern city.