The Railway Caponier is an independent fortification structure that was part of the Poznań Fortress, built in 1872 with the purpose of protecting railway lines in the directions of Toruń and Stargard. Situated beneath the exit road from the Berlin Gate, it was well-suited for firing, offering vaulted rooms for five cannons and positions for riflemen. The walls of the structure featured embrasures, highlighting its military functions.
Between 1968 and 1973, the Mikołaj Kopernik roundabout with an underground passage was constructed on the site of the Railway Caponier. Although the structure was partially demolished—the eastern part of the caponier was destroyed—the remainder, including casemates covering an area of 340 m², was preserved. During World War II, these casemates served as shelters and were later converted into a wine warehouse after the war.
Today, the Railway Caponier is located beneath the University Bridge, and nearby is the Rondo Kaponiera stop, which serves as a transfer point for the Poznań Fast Tram and provides convenient access to the PKP railway station. The caponier's days of glory are now history, but its remains still bear witness to the rich past of this location, attracting the attention of both residents and tourists.