Stones End fort
A parliamentary fort erected to defend London during the Civil War.
The picture source website is fascinating but strangely we can't actually locate Stones End on the maps there. There used to be a concrete map, 'Lines of Communication', in Bishop’s Square, Spitalfields which shows the Civil War fortifications around London and that didn't show Stones End either. 2015: Matt at Londonist has walked the northern section of the Civil War defences. 2017: IanVisits has a good post and is doing the whole circuit.