The Boryszyn Loop (polish "Pętla Boryszyńska") consits of many different objects and therefore is the most interesting area of the Miedzyrzecz Fortified Region (sometimes also called "Ostwall"). Beside Bunkers a mysterious underground world composed of railway stations, barracks, work shops, engine rooms and ammunition magazines can be discovered.

The Boryszyn Loop was built between world war 1 and 2 and later fell into oblivion. Now the Boryszyn Loop is accessible again.