The Barbican was built around 1498, out of fear of a Turkish invasion after King John Albert’s defeat in Bukovina. It is one of three surviving barbicans in Europe and the best preserved of them.
The structure is circular, more than forty metres across, with walls close to three metres thick and seven observation turrets. Over a hundred and thirty loopholes are set into the masonry. A moat originally surrounded it, and a fortified passage connected it to the Florian Gate.
The Barbican was never taken, because the siege it was built for never came. It is now a branch of the Museum of Kraków and in summer serves as a venue for open-air events.