The medieval open hall house had an open hearth in the middle of the floor and was open to the rafters with no upper floor.
Welsh tower houses, rectangular structures, consisting of two or more storeys, are closely related to those in Ireland and Scotland.
In 1976 Hilling produced a map (with listing) showing 17 examples.
These include Owain Glyndŵr's Parliament House in Machynlleth.
Most examples are found in southern Wales with a cluster of buildings in Pembrokeshire.
The distribution of Tower and other houses in Wales with vaulted ceilings have been mapped and listed by Peter Smith.