There's an open tunnel section at the back of Argyle Street, west end (behind the small 2 storey house, no. 1129 a block up from Creme de la Creme)
I used to work there and the only access is at the back of 1129 or round to the right of the back lane (access at no. 1103)
Its a fair drop down to it so I never explored it at all but has anyone been down? And what line does that connect with?