Describing the countryside

While driving up to John O'Groats, the northern most part of Scotland, Sandra was unable to pay too much attention to all the marvelous things flying past us.  At one time we were passing a strange looking triangle-like stone wall beside a cliff, through the wall was a hole or an opening through which a train might have passed at one point or another.  Considering that it was not being used as such any longer it was strange to see something stand like this so abandoned in the landscape. Catriona did her best to describe it to Sandra:

'There is a triangle thing with a thing in it'
Catriona, 2008