How was Hadrian's Wall built?

Alastair Moffat gives us this description of the basic construction

" The core of the Wall was filled by rubble,clay and soil laid between two outer skins of masonry.Lime mortar was used for bonding."

He then talks about the evidence for lime kilns and the dangers of this production process.

Next question regards the height of the wall. At 4 metres high the Romans would have needed scaffolding or ladders. And then there were the mile castles and turrets which were even higher.

Experts are said to have estimated that over 150,000 metres of straight cut wooden poles would have been required.

So between 122 ans 123 AD there must have been an awful lot of trees which were felled.

A real change for the Northumberland landscape.