The Warsaw Barbican was created as the city gate in the 1500’s as part of a general repair of the city walls. It was designed by Jan Baptist, a Venetian. You can clearly see the Venetian style in the design. The irony is that the city walls became useless almost as soon as they were repaired. This was due to modern cannon which could blow straight through the walls.
There’s a great Wikipedia article if you want to find out more.