Our sense of humour, devised to cause confusion amongst the English! One just has to visit Cwm Ebbw Vale to understand. My family come from Cwm Road, Aberbargoed. You need one leg shorter than the other to stand upright outside the house.
Chris - in terms of capturing the atmosphere, I would maybe avoid Aberbeeg, it is quite a feature, but specific. If I think about retaining walls then I think about Sunnybank Rd Blackwood, this drops down to the old main road behind a high retaining wall. Llanhilleth, especially in front of the school, or as someone has mentioned in another context (Paddywagon trains), Big Arch at Talywain. The feature is the dressed stone and its colour. I remember reading an Iain Rice article once (he is very familiar with Talywain/Varteg) where he said that you should be able to remove the rolling stock and tell the company and the generic location. Valleys architecture is perculiar to the area and hence this will give viewers the sense of location. It is what I'm trying to develop myself.
Regards.