Western Heights, Dover 
“A huge fortification begun during the Napoleonic Wars and completed in the 1860s, designed to protect Dover from French invasion. Only the moat can be visited.…” – official site
Ease by public transport:
Unknown
“A huge fortification begun during the Napoleonic Wars and completed in the 1860s, designed to protect Dover from French invasion. Only the moat can be visited.…” – official site
Ease by public transport:
Unknown