Penstrowed is situated in the river
Severn valley. The founder of the church,
Saint Gwrhai was a 5th-century saint who is supposed to have been buried in the churchyard. The Penstrowed Quarry was an important source for local stone and was used for building the
Caersws workhouse. It was later acquired by Montgomeryshire County Council and a railway siding connecting the quarry to Cambrian main line laid in 1902 and closed in May 1937. Penstrowed now claims to be 'The smallest hamlet in Wales'. It is governed by the Mochdre with Penstrowed Community Council. Until 1 April 1987 Penstrowed was a community itself.
Eiluned Lewis (1900–1979), a Welsh novelist, poet, and journalist came from here. ==Church==