One of the more ingenious features of pagan Baltic defences against the Crusaders was the kūlgrinda, a secret road hidden beneath the water of a swamp — Andrius
These were stone-paved passages, sometimes wide enough for horses and carts, allowing local warriors to move between fortifications or escape advancing armies. To an outsider, the road was practically invisible. A wrong step could send a man into deep bog mud.
During the 13th and 14th centuries, such passages formed part of the defensive infrastructure of Lithuania and Samogitia. Several kūlgrindos have survived to this day, particularly in western Lithuania, although many others have been lost or remain undiscovered.
One of the best-known examples is the Sietuva kūlgrinda. In 1903, archaeologist Ludwik Krzywicki investigated it and noticed something peculiar: rather than taking the shortest route across the swamp, it deliberately twisted through low-lying ground. He concluded that the builders wanted to make the road difficult for enemies to follow.
Three surviving stretches at Sietuva measure 250, 180 and 150 metres. They are thought to have formed part of a secret route connecting the fortresses of Medvėgalis, Paršpilis and Šiuraičiai
