Castle building for military reasonscame to an end at about 1500because of gunpowder and explosives being invented.
When guns, cannons, howitzers, artillery and bombs became powerful enough to destroy any built structure, the castles became pointless from a military perspective.
Castles kept being built every now and then mainly for Propaganda and/or romantic reasons. If you're a country, it can be good to show that you're wealthy enough to afford to build something huge and impressive, even if it isn't that useful any more.
The Roman did not have any castles. Castles emerged after the end of Roman civilisation, during the Middle Ages.
TRebuchet and catapult
Cannon and gunpowder.
They had outlived their usefulness and were no longer needed
The oldest medieval castles were made in the 9th century AD. They were made until the end of the middle ages.
The usefulness of stone castles came to an end with the invention of the cannon - the Turks used these with great success during the Crusades - if my memory serves me well.
the invention of the cannon
Because cannons were invented that blew out the walls therefore they were no use
mote and bailey castles and stone keep castles and Concentric Castles
the first kind of castles were moat and bailey castles.
beacause it was the start of the war of the roses
a castle