Arminghall is one of those sites that looks like nothing today, but in its time would undoubtedly have been pretty astonishing.
Like Woodhenge, its potential was spotted from the air by brave military pilot Gilbert Insall, who snapped it with his camera. Grahame Clark excavated it in 1935 – he found eight enormous post holes in the middle of the henge. Each was equipped with a slope to help manoeuvring (you can see these in the diagram posted by KK), and they were arranged in a horseshoe, with the open part next to the henge entrance.
The two holes that Clark excavated most thoroughly had post pipes nearly 1m across. Post pipes are the traces in the soil of rotted timber posts – so the oak timber posts must have been Enormous.
Considering Maud Cunnington thought her 85cm postpipes at Woodhenge translated into posts rising 7.5m above the ground and weighing 5 1/2 tons – well, Arminghall must surely have been a stupendous sight.
Though this may take some imagining considering its current environment.
(gleaned from Mike Pitts’ ‘Hengeworld’)