Principality of Wales

The Craig Goch Dam, often called the Top dam, is a masonry dam in the Elan Valley of Wales and creates the upper-most of the Elan Valley Reservoirs. Construction on the dam began in 1897, and it was completed in 1904. The primary purpose of the dam and the other reservoirs is to supply Birmingham with water. In 1997, a 480 kW hydroelectric generator began operation at the dam.

The Elan Valley (Welsh: Cwm Elan) is a river valley situated to the west of Rhayader, in Powys, Wales, sometimes known as the "Welsh Lake District". It covers 70 square miles (180 km2) of lake and countryside. The valley contains the Elan Valley Reservoirs and Elan Village, designed by architect Herbert Tudor Buckland as part of the same scheme. Elan Village is the only purpose-built Arts and Crafts "Model Village" in Wales. It is also famous for its picturesque scenery. Over 80% of the valley is designated as Sites of Special Scientific Interest, and a popular cycle trail, the Elan Valley Trail, makes a loop from Rhayader around the reservoirs. Part of the trail overlaps with a spur of National Cycle Route 81 (Lon Cambria). As of 2015 it is an International Dark Sky Park.

Elan Village (Welsh: Pentre Elan) is a small purpose-built community in Powys, Wales. It was designed by architect Herbert Tudor Buckland as part of Birmingham Corporation's scheme to construct a series of water supply reservoirs in the Elan Valley between 1892 and 1904. It housed workers and their families responsible for maintaining the scheme's dams and the filtration systems. Elan Village is the only purpose-built Arts and Crafts "Model Village" in Wales. It is served by the B4518 road which runs three miles southwestwards from Rhayader to end at the village, though continuing as a minor road to Caban-coch Reservoir. The road continues over the Elenydd to Cwmystwyth and a cul-de-sac branch runs to the dam of Claerwen Reservoir. It is in the community of Rhayader.

Caeau Cnwch a Ty'n-y-graig is a Site of Special Scientific Interest in Brecknock, Powys, Wales. It occupies sloping ground on the south west side of Pen-y-garreg Reservoir in the Elan Valley. Caeau Cnwch a Ty'n-y-graig comprises four traditionally managed fields in a small valley below Craig Cnwch, near Elan Village. They provide a type of herb-rich grassland that is characteristic of the upland fringe of central Wales.

Carn Gafallt is a Site of Special Scientific Interest in Breconshire, Powys, Wales, and a hill of 466 metres (1529 feet) which is a Marilyn.

Marteg Halt railway station was a station to the northwest of Rhayader, Powys, Wales. The station closed in 1962.

Garreg Lwyd is a hill in Mid Wales, between the towns of Rhayader and Llangurig. It rises to the east above the A470 as it follows the Wye Valley. The Bryn Titli Wind Farm is situated on an area of flatter moorland to the north-west. Red kites frequent the area.

The Claerwen Fault is a major SW-NE trending fault in central Wales. It was active as a normal fault during deposition of Late Ordovician to mid-Silurian sedimentary rocks, downthrowing to the northwest. The estimated throw on the fault increases from about 100 m at a shallow level to about 1000 m at depth. There is no discernible change in the grade of metamorphism associated with the Caledonian Orogeny across the fault, suggesting that it was not reactivated later.

The Afon Marteg is a river in Powys, Wales. It is about 15 km long, flowing roughly south-west to join the Wye at Pont Marteg (grid reference SN952714) about 5 km above Rhayader.Fishing is available, with appropriate permits, for brown trout, chub, dace, grayling and pike. The river has a run of spawning Atlantic salmon in the autumn.

Rhayader railway station was a station serving the town of Rhayader, Powys, on the Mid Wales Railway line. It was opened in 1864 in Cwmdauddwr, a village on the opposite bank of the River Wye. The line, which took over 5 years to build, was closed in 1962 and dismantled within months. The station was the junction for the Elan Valley Railway which was in operation between 1896 and 1916. The site of the station is now occupied by Powys county council's highways department.

Cwmdauddwr (rarely referred to by its correct full name of Llansanffraid Cwmteuddwr) is a village in Powys, Wales. It is contiguous with the town of Rhayader on the opposite side of the River Wye. The village is located on the B4518 road linking Rhayader with the Elan Valley Reservoirs. The parish of Cwmdauddwr corresponds approximately to the medieval commote of Cwmwd Deuddwr (Welsh for 'Commote of the Confluence'; lit. 'commote of the two waters'). It was so called because of its location where the rivers Elan and Wye join. It has also been referred to as Elenydd and Elenid. It was in the area known as Rhwng Gwy a Hafren. It was also associated with Gwrtheyrnion on the east of the Wye, together they formed a cantref. This commote should not be confused with the commote of Deuddwr in Ystlyg which is also in Powys. The village is home to a pub (The Triangle Inn), village hall and a parish church dedicated to St Bride (Welsh: Sant Ffraid). The Groe, a large park on the banks of the river, has walks, play areas and sports pitches. Rhayader railway station was situated in the village until its closure in 1963.

The Afon Elan (English: River Elan) is a tributary of the River Wye which runs through the wide expanse of upland moors, traditionally known as Elenydd, in central Wales. Its valley is the Elan Valley. The name probably arises from elain meaning 'hind' or 'fawn' in reference perhaps to the rushing, bounding nature of its course.It has its source in wet moorland on the eastern flank of Pen y Deunant in Ceredigion. It is joined by Nant Dderwen, Nant Cwta and Nant Hirin before entering the top of the Elan Valley Reservoirs at Craig Goch Reservoir which in turn discharges to Garreg-ddu Reservoir and then Caban-coch Reservoir. It emerges from this chain of reservoirs in a north-easterly direction and passes through Elan Village before turning south-east after 2 miles and making its confluence with the River Wye.