hi

It isn't so much "close" to Valley, as under it. It's more of a puddle now than a lake. It is on RAF land at the airbase, and as you say is marked by a boulder and plaque. Most of the finds are in the National Museum in Cardiff.

As far as the keys go, Bryn Cellis Ddu doesn't need a key, and the key to Barclodiad y Gawres is still at the shop.

sam