### castle and fortification architecture
As a result of the rapid spread of increasingly modern firearms in the 16-17th century (the various cannons and rifles) the medieval fortresses and castles were no longer suitable for defence with their high and thin walls. As a consequence the building of fortresses significantly altered first in Italy and by spreading from there it reached nearly all of Europe including the Habsburg empire's anti-Turk theatre of combat in Hungary. The medieval hill castles built with tall walls which were easy to blast down were replaced by short, mostly pentagon or hexagon shaped modern fortifications with very strong stone walls that had large defence banks and giant forts. Forts were planned in such ways by the most experienced Italian and Dutch as well as in the 17th century French military engineers, that the neighbouring castle wall and fort could be covered from it in the best way possible. The building of fortifications in Hungary were only occasional and rapid up until the mid 1550's, however, this has changed into a structured building technique which accepted the advice of the most excellent Italian master builders. The most significant Hungarian fortifications were the ones in Érsekújvár, Károlyváros, Győr, Szatmár, Eger and Várad. PG