Warsaw: Barbican.

“The barbican (semicircular fortified outpost) is one of few remaining relics of the complex network of historic fortifications that once encircled Warsaw. Located between the Old and New Towns, it was erected in 1540 in place of an older gate to protect Nowomiejska Street. It was designed by Jan Baptist the Venetian, an Italian Renaissance architect who lived and worked in the Mazowsze region of 16th century Poland and was instrumental in the redesign of the 14th-century city walls, which by that time had fallen into disrepair.”