Regenwurmlager

Regenwurmlager in Kęszyca is the colloquial name for part of the Festungsfront Oder-Warthe-Bogen, also known as the Festung im Oder-Warthe-Bogen or Ostwall, and in Polish as the Międzyrzecki Rejon Umocniony (MRU). This fortified military defence line of Nazi Germany lies between the Oder and Warta rivers, near Międzyrzecz, and was built in 1934–44. It is a place for exploring historic fortifications and going on a short visit underground.

• You can see a large defensive system made up of around 100 concrete fortifications, many of them linked by a network of tunnels.
• The site is notable for being the most technologically advanced fortification system of Nazi Germany, and it still ranks among the largest of its kind in the world.
• Some of the forts and tunnels are open to visitors, so you can experience the scale of the complex from the inside rather than only from the surface.

If you plan to go, it is worth bringing comfortable shoes and checking opening times in advance, especially if you want to visit the tunnels. This is a good choice for travelers interested in military history, underground routes, and a more unusual sightseeing stop.