Fortified settlements are often monuments of long existence. Being built originally by one group with a specific purpose, they might change in appearance, function or cultural affiliation over time. The lecture emphasises the necessity of proving contemporaneity for the interpretation of systems of fortifications, by showing case studies from the Russian Kaliningrad district. Here, large numbers of so far mostly unstudied hillforts are concentrated within a limited, but rich in archaeological sites landscape, showing settlement traces from Bronze Age until Medieval times. By applying the method of ‘speed-dating’, a combination of drilling and C14 dating conducted at the embankments, several hillforts in those agglomerations were recently dated by the author. The resulting ‘heartbeat of hillforts’ made it possible to identify contemporary hillforts and allow for a detailed interpretation of the relation between the strongholds, sometimes also hinting at their probable function.