The tradition of building in stone was continued into Iron Age with the establishment of such hill forts as those at Tre'r Ceiri in North Wales and Garn Goch in the south.
The Cambrian Caerbwdi sandstones may be seen in St David's Cathedral whilst Ordovician slates from northern Pembrokeshire were once an important local roofing stone.
The Cambrian and Ordovician slates of North Wales were once worked on a huge scale and the evidence of the former industry is considerable, especially around Llanberis, Bethesda and Blaenau Ffestiniog.
The Pennant Sandstone is widespread around the South Wales Coalfield where it has been extensively worked to provide building stone for everything from field walls, though the terrace housing typical of places like the Rhondda to edifices such as Crawshay's Cyfarthfa Castle at Merthyr Tydfil.
The Quarella Stone from Bridgend has been used at Kidwelly Castle for example whilst a red conglomerate from Radyr quarries is to be found in service at Penarth docks.