The development of firearms ended the castles' endurance. Another reason is when abandoned they could quickly be reduced to rubble by local people using them as a source of dressed stone and other building materials.
There are no genuine medieval castles in the USA, because the Americas were not discovered until after the medieval period had ended. There are the "fairytale" Disney castles and some modern attempts at reconstructing medieval castles, but no genuine ones.
Because cannons were invented that blew out the walls therefore they were no use
Underground Development ended in 2010.
Massive Development ended in 2005.
Castle building ended when they were no longer able to be defended. In the 15 century, artillery such as cannon balls and mortar were able to break through the stone walls.
Bristol Development Corporation ended in 1995.
Rural Development Service ended in 2006.
Leeds Development Corporation ended in 1995.
Port Development International ended in 2002.
Canada Development Corporation ended in 1986.
Merseyside Development Corporation ended in 1998.