Nant Y Wern (Pant Serthfa)

View from north east (Scale 1m).

A single stone row measuring at least 5.95m and possibly 29m long, including at least four or six small and medium-sized stones situated on a gentle south facing slope. The row is orientated north to south and is built across the limit of visibility to Cefn yr Ystrad.  The row is also at the limit of visibility to Pen y Fan.


 Wales     Powys     Brecon Beacons     SO 11848 16732     Lat 51.8422   Long -3.28076

Map showing location of Nant y Wern

Plan of Nant y Wern stone row (Source: survey by Sandy Gerrard at 1:100).

Plan showing the position of the two smaller stones relative to the four large stones (Source: survey by Sandy Gerrard at 1:100).


Type: Single Length: 29m
No. of stones: 6 Size of stones: Small and medium
Orientation: 6° Altitude: 481m
Upper end: – Lower end: –
Straight (Yes or No)  : Yes Sea View: No
Context:  Cairns
Notes: Also known as Pant Serthfa

Other Information

Public Access:  Yes
Land Status: National Park
Scheduled Ancient Monument: BR374


Category: Plausible. Despite early concerns regarding the interpretation of this monument there appears to be a consensus that it is a prehistoric stone row. It is generally described as a short four-stone row, but fieldwork has identified a further two small stones on the same alignment as the larger ones and these may also have formed part of the row.


This stone row is of Type S7. Information on this form of stone row and other rows of this type is available here.


View from south showing the location of the row.

View from west (Scale 1m).

View from east (Scale 1m).

View from south east (Scale 1m).

View from south west (Scale 1m).

Looking south along the row (Scale 1m).

Individual Stones

Plan of Nant y Wern showing the stone numbers.

Stone 1 measures 1.43m long by 1.10m wide and stands up to 0.4m high.

Stone 2 measures 1.47m long by 0.35m wide and stands up to 0.46m high.

Stone 3 measures 0.50m long by 0.46m wide and stands up to 0.71m high.

Stone 4 measures 0.97m long by 0.38m wide and stands up to 0.5m high.

Stone 5 measures 0.20m long by 0.17m wide and stands up to 0.08m high.

Stone 6 measures 0.24m long by 0.19m wide and stands up to 0.07m high. View from south (Scale 1m).

Stones 5 and 6. Stone 6 is beside the ranging rod and Stone 5 is on the far right of the photograph. There are no other stones in the vicinity and as both are on alignment with the larger stones there is a stong possibility that they form part of the row. Perhaps some (or even all) of the apparently shorter rows composed of larger stones were originally much longer and were mainly formed by small stones which in most instances either no longer survive or are buried. 

Landscape Reveal

A landscape reveal that may be of significance exists at Nant y Wern. A rocky outcrop at Cefn yr Ystrad is visible from the three northern stones and vanishes at the fourth stone. To all intends and purposes it looks like a large skyline cairn which seems to grow in size as you walk north along the row.

The stone row and Cefn yr Ystrad. View from north east.

Cefn yr Ystrad disappears from sight at Stone 4.

View of Cefn yr Ystrad from Stone 3.

View of Cefn yr Ystrad from Stone 2. As you walk northward it grows in size.

View of Cefn yr Ystrad from Stone 1. FRom this distance it resembles a large skyline cairn.

Pen y Fan

The row is built at the limit of visibility to Pen y Fan.  This may have been a contributory factor in the choice of site.

View of Pen y Fan from the Nant y Wern stone row. 

Access Information

Limited car parking is available at SO 11954 12966. From here walk along the private road to SO 11152 14998 and then follow the footpath north to the row. Alternatively the row may be accessed from a large car park at SO 15698 17094.

Online Resources 

Megalithic Portal     Modern Antiquarian     Coflein     Archwilio


VISITED:- 5th September 2018

FIRST PUBLISHED:- 27th January 2016

LAST UPDATED 18th March 2019

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