Dover Castle Canons Gate (Historic Document)

My historic document into the 1790's gateway Canons gate, all my research go to:

English Heritage:
1997 - Jonathan Coad
2012 - Steven Brindle

Department of the Environment:
1975 - R. Allen Brown.

many thanks to Subterranean History, for the Martello Tower photos.
http://www.subterraneanhistory.co.uk/

For great sound effect visit:
https://www.youtube.com/user/YTSoundEffects