This is a photo of Milecastle 48,at Poltross Burn,by Gilsland.Milecastles,housed the soldiers who patrolled the Wall.Each Milecastle housed between 30 and 50 auxiliary soldiers,for,whilst the Wall was built by the Legions it was policed by the auxiliary soldiers.Each milecastle had a circuit wall with two barrack blocks,either side of a central "street".Entry to and exit from the milecastle was intended to be through policed gates at either end of the milecastle,but as time went by,and trade "routes" became established through the Wall,some milecastle gates were partially blocked up to encourage trade through more easily patrolled points.In this photo is an example of one such partially closed gateway.NNB:The height of the walkway on The Wall has been conjectured from the one piece of evidence,still in situ,at this milecastle.In the shade in the far distance/bottom of the foundations rhs,just out of the sunlight,is a sequence of stone steps.It is believed that these steps led up to the wallwalk,and the height of The Wallwalk has been conjectured from this.