Star forts evolved during the age of black powder and cannons in the 16th century. The traditional medieval circle forts proved to be vulnerable to cannon fire. Star fortifications were first introduced in Italy in the mid 15th century. The wall were made of brick because the bricks don't shatter like stone when struck by a cannon ball.

These forts still stand today, many are empty or ruins some have villages in them.

Palmanova, Italy

Bourtange, Netherlands

Goryokaku, Japan

Almeida, Portugal

Saint Martin-de-re, France

Naarden, Netherlands

via obromley.co.uk, cc.gatech.edu, Wikipedia

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