Because Gunpowder made the walls obsolete as a means of defence.
KFAZ - defunct - ended in 1955.
KWTR - defunct - ended in 2011.
WYOO - defunct - ended in 1976.
Medieval castles.
The Roman did not have any castles. Castles emerged after the end of Roman civilisation, during the Middle Ages.
Stone castles have many small spaces between each other. As the space becomes bigger, the stone castles become weaker an weaker.
There are different reasons as to why castles became palatial. One main reason is because castles were no longer needed for defense, therefore were turned into palatial castles where people were free to visit and stay in.
Artillery (Cannons) could collapse them.
The Nash Automobile Company is defunct.
WIAR - defunct - was created in 1922.
KWOD - defunct - was created in 1957.
KWOD - defunct - ended in 2009.
WGTL - defunct - was created in 1946.
WGTL - defunct - ended in 1992.
WEEP - defunct - was created in 1936.
WAWA - defunct - was created in 1965.
KNOB - defunct - was created in 1957.