Coalhouse Fort is an artillery fort in the eastern English county of Essex and occupies a strategic location on the north bank of the River Thames, fronted by a moat and saltmarshes. It was built in the 1860s to guard the lower Thames against seaborne attack. It stands at Coalhouse Point on the north bank of the river, at a location near East Tilbury that was vulnerable to raiders and invaders.
It is open every last Sunday of the month between March and November.
If you consider buying a drone would suggest reading this blog post first.