Abercarn Colliery Junction (Unclassified).
Grid Reference: ST 21432 94182. Parish: Abercarn, Monmouthshire
When recorded: 1898-1908. Primary Source: OS 2nd Edition Maps. Secondary Source: GB1900 website

Abergwawr Colliery (Unclassified).
Grid Reference: SO 01518 01406. Parish: Aberdare, Glamorgan
When recorded: 1898-1908. Primary Source: OS 2nd Edition Maps. Secondary Source: GB1900 website

Adare Colliery (Unclassified).
Grid Reference: SS 89883 84165. Parish: Ynysawdre, Glamorgan
When recorded: 1898-1908. Primary Source: OS 2nd Edition Maps. Secondary Source: GB1900 website

Adare Colliery (Disused) (Unclassified).
Grid Reference: SN 88689 05003. Parish: Blaengwrach, Glamorgan
When recorded: 1898-1908. Primary Source: OS 2nd Edition Maps. Secondary Source: GB1900 website

Afon Collen (Unclassified).
Grid Reference: SH 86170 67717. Parish: Llangernyw, Denbighshire
When recorded: 1898-1908. Primary Source: OS 2nd Edition Maps. Secondary Source: GB1900 website

Afon Collen (Unclassified).
Grid Reference: SH 84406 67244. Parish: Llangernyw, Denbighshire
When recorded: 1898-1908. Primary Source: OS 2nd Edition Maps. Secondary Source: GB1900 website

Albion Colliery (Unclassified).
Grid Reference: ST 08448 92591. Parish: Pontypridd, Glamorgan
When recorded: 1898-1908. Primary Source: OS 2nd Edition Maps. Secondary Source: GB1900 website

Allotment open to Mr Colly's (Field).
Grid Reference: SO 05824 88164. Parish: Mochdre, Montgomeryshire
When recorded: 1841. Primary Source: none. Secondary Source: Cynefin

Allt-wen Colliery (Disused) (Unclassified).
Grid Reference: SS 58100 96386. Parish: Gowerton, Glamorgan
When recorded: 1898-1908. Primary Source: OS 2nd Edition Maps. Secondary Source: GB1900 website

Ammanford Colliery (Red Vein) (Unclassified).
Grid Reference: SN 64871 11814. Parish: Betws, Carmarthenshire
When recorded: 1898-1908. Primary Source: OS 2nd Edition Maps. Secondary Source: GB1900 website