Museum Biržai Radziwiłł Castle in Biržų rajonas

You're standing at Biržai Castle, in the north of Lithuania. Don't expect turrets and battlements. This is mostly a fortress made of earth: wide ramparts with sharp, pointed corners called bastions. It was the first Italian-style bastion fort in Lithuania, and one of the first in all of North-Eastern Europe. Look at how those corners jut outwards. That shape let defenders fire at attackers from the side.