Bryn Eryr was a small Iron Age farmstead near Llansadwrn in the eastern corner of Anglesey. During the Bronze and Iron Ages in Britain, roundhouses were the most common form of home. These roundhouses are reconstructions based on the archaeology of the original houses which were excavated by the Gwynedd Archaeological Trust between 1985 and 1987. The excavations revealed three substantial roundhouses. The earliest and largest house was built during the Iron Age and enclosed by a timber stockade. The second roundhouse, probably built shortly before the Roman invasion was placed right next to the first while the stockade was upgraded to a more permanent rectangular-shaped bank and ditch. During the first millennium AD, as the banks were eroding and the ditch silting, a third house was built on stone footings.     

Bryn Eryr is an experimental reconstruction of the earliest two houses, and due to their close proximity to each other, it is quite likely they formed one building with two rooms. Such buildings, sometimes called figure-of-eight, or conjoined roundhouses, have only recently been identified, and consequently very few reconstructions have been attempted. Moreover, the Bryn Eryr roundhouses have walls of rammed clay 1.8m thick – a first for reconstructed roundhouses. 

Interpreting and reconstructing the archaeology of Bryn Eryr posed considerable challenges. For instance, did this building have two conical roofs - one for each room? Or, did it have a shared roof that spanned both cells? After much deliberation, a roof was built of two cones and joined by a low section of roof over a linking passage. Yet another experimental technique was used to thatch the roof. Called ‘thrust’ thatching: an under-thatch of gorse was laid onto the framework of the roof, and a layer of wheat straw (the ‘topcoat’) was then thrust into the under-thatch, hence the name. 1500 volunteers helped build Bryn Eryr.  

Bryn Eryr Iron Age Farmstead at St Fagans National Museum of History

Bryn Eryr Iron Age Farmstead at St Fagans National Museum of History

Bryn Eryr map plot

Building facts:

  • Basis for reconstruction: Archaeological excavations at Bryn Eryr, Anglesey
  • Date of original buildings: around 2,000 years ago
  • Visiting information