Krakow Barbican is a Gothic defensive outpost built in 1498-1499 and one of the best-preserved in Europe. The cylindrical brick structure features 130 arrow slits, 7 watchtowers, and walls 3 meters thick. It protected the northern entrance to the city and was connected to the Florian Gate by a narrow passage. Today it serves as an exhibition space and cultural events venue. A visit takes about 20-30 minutes but the building is well worth seeing for its impressive scale and engineering of medieval defensive architecture