A spigot mortar emplacement at the north west corner of Eltham Common (in the trees at the corner of the buildings), Shooters Hill, London.
This spigot mortar featured in Series 15, Episode 6 of Time Team where the surrounding trench and cast iron revetment were excavated.
https://archaeologydataservice.ac.uk/archives/view/dob/ai_full_r.cfm?refno=6759
166 photos taken in June 2022 with a Sony a7R III and processed in Reality Capture.