The A4109 road links Aberdulais

Aberdulais

Aberdulais or mouth & Dulais) is a village in Neath Port Talbot, Wales, lying on the River Neath.- History, amenities & attractions:...

 with Glynneath

Glynneath

Glynneath , also spelt Glyn Neath, is a small town, community and electoral ward lying on the River Neath in the county borough of Neath Port Talbot, Wales. It was formerly in the historic county of Glamorgan...

 in Neath Port Talbot

Neath Port Talbot

Neath Port Talbot is a county borough and one of the unitary authority areas of Wales. Neath Port Talbot is the 8th most populous county in Wales and the third most populous county borough....

 county borough, Wales

Wales

Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...

.

The route begins in Aberdulais

Aberdulais

Aberdulais or mouth & Dulais) is a village in Neath Port Talbot, Wales, lying on the River Neath.- History, amenities & attractions:...

 at the junction with the A4230

A4230 road

The A4230 is a suburban main road in south Wales.The A4230 is a single carriageway road for its whole length. It begins at the Peniel Green roundabout in the far east of Llansamlet...

 and A465 road

A465 road

The A465 is a major road in south Wales. It is more commonly known as the Heads of the Valleys Road because it joins together the north ends of the South Wales Valleys...

s; it diverges northwards away from the A465 up the Dulais Valley

Dulais Valley

The Dulais Valley, one of the South Wales Valleys is traversed by the River Dulais in southwest Wales north of the town of Neath.Settlements in the valley include Crynant, Seven Sisters, Banwen and Dyffryn Cellwen which are served by the A4109 road though the valley.The towns in the valley...

 and crosses through the settlements of Crynant

Crynant

Crynant is a village in the Dulais Valley, lying between the mountains of Mynydd Marchywel to the west, Hirfynydd to the east and Mynydd y Drum to the north. It lies 7¾ miles north-east from the town of Neath in Neath Port Talbot, Wales....

, Ynysfforch, Seven Sisters, Onllwyn

Onllwyn

Onllwyn is a small village in Neath Port Talbot, Wales, near Seven Sisters.-History:First developed by the Romans, local village Banwen is confined to the Roman Road of Sarn Helen. There are two Roman forts and the remains of a Roman Road within the community.Legend has it that St Patrick was born...

, Dyffryn Cellwen

Dyffryn Cellwen

Dyffryn Cellwen is a village in the County Borough of Neath Port Talbot, South Wales. It is situated in the upper Dulais Valley near the junction of the A4109 and A4221 roads, northwest of the smaller settlement of Banwen...

 and Banwen

Banwen

Banwen is a small village in Neath Port Talbot county borough in Wales. Banwen is part of the community of Onllwyn along with the village of Onllwyn itself and the adjacent parish of Dyffryn Cellwen...

 where it has a junction with the A4221

A4221 road

The A4221 is an A road which links Banwen with Abercraf in Wales.The roads begins just south of Abercraf at the junction with the A4067. It then heads eastwards through Caehopkin and then bypasses Coelbren. It joins the A4109 just west of Banwen....

. The road then continues in a southeasterly direction along the Inter Valley Road to Glynneath where it again connects with the A465

A465 road

The A465 is a major road in south Wales. It is more commonly known as the Heads of the Valleys Road because it joins together the north ends of the South Wales Valleys...

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