What year were the great English and Welsh castles being abandoned unnecessary and falling apart?

The great English and Welsh castles began to be abandoned and fall into disrepair primarily during the late 17th and 18th centuries. As the need for defensive strongholds diminished and political stability increased, many castles were no longer maintained. Additionally, the rise of more modern architectural styles and residential needs contributed to their neglect. By the 19th century, many had become romanticized ruins, often attracting visitors as historical sites.