Mamonovo (Мамоново) is a town in Kaliningrad Oblast, Russia. Under the Teutonic Knights Heiligenstadt was built near an Old Prussian settlement. It was later renamed Heiligenbeil after a holy axe used by Augustinian monks, established in the area by Grand Master Winrich von Kniprode after the Battle of Rudau, to cut down an oak tree worshiped by pagan Prussians. It is situated south-west of Kaliningrad.
Mamonovo has a population of over 7,761 people.