County map collections of Brecknockshire, Radnorshire and Montgomeryshire from the 16th, 17th, 18th and early 19th Centuries are kept by the three County Museums. These are engraved maps which can be quite detailed. The County Museums may also hold maps of Turnpike Trust Roads dating from the second half of the 18th Century.
The County Archives Office has card indexes indicating which maps are available for each parish, and on which sheet of the OS 6" scale series the village which gives the parish its name can be found.
There exist two maps indicating the ancient parish boundaries, which are very useful, as not all of the old boundaries correspond to the modern parishes, particularly in the border areas, where for example certain Shropshire parishes straddled the border into Montgomeryshire.
Parish and some other records refer to the old boundaries