When did they build dover castle?

Answer 1

Dover has been inhabited and fortified for centuries as it is a port at the narrowest section of the English Channel. Iron Age defenses were built over by the Romans, who constructed a lighthouse. On his way to London in 1066, William the Conqueror had a castle built here, and his descendant Henry II expanded upon it in the late 1100s. Modifications were made after vulnerabilities were revealed in the 1216 siege by the French. Georgian military engineers modified the works in from the mid 1700s to the early 1800s to deal with gunpowder weaponry, and extensive tunnels were dug under the castle in the 20th century to protect command facilities from aerial and nuclear attack. So Dover Castle has a delightful variety of military architecture. SOURCE:http://johnsmilitaryhistory.com/dover.html

Answer 2

William the conqueror built dover castle in 1066