Defensive buildings are buildings with an attack capability or, in case of walls and gates, with enough HP and armour, which can be utilized in defense of an area, to block an enemy's advance or to deny ground to an opponent, among other uses.
“The Guild Hall is available to Bavaria, Flanders, Genoa and Saxony from the 13th Century...Guild Hall
“A Stone Wall is a basic fortification first available in the 13th Century. Walls keep enemies...Stone Wall
“When a player installs a Town Watch, (s)he gains the ability to build Watch Towers. Their role...Watch Tower