Good quiz, never heard of the 'Quonset Hut'......... in UK was known as a "Nissen Hut'. Originally designed during the First World War by the engineer and inventor Major Peter Norman Nissen, it was used extensively during the Second World War.
I was surprised it is so low. They still sell them in the US and I see a lot of them around here for grain storage, or for road departments storing sand.
I knew the answer was quonset, but couldn't spell it for the life of me. I must have tried 15 different spellings, but never got the right one. I think most of the spellings I tried started with qua...