The church of St. Garmon ([[St. Germanus]]) is thought to be of early-mediaeval origin; it was 'restored' in 1886 to designs by W. H. Spaull of [[Oswestry]].<ref name="llanfylin"/> The area was historically part of the parish of [[Llanrhaeadr-ym-Mochnant]] but eventually became a separate [[township (England)|township]].<ref name=cpat>[http://www.cpat.org.uk/projects/longer/histland/tanat/tnadmini.htm Tanat Valley], Clwyd-Powys Archaeological Trust</ref> It is now part of the [[community (Wales)|community]] of Llanrhaeadr-ym-Mochnant for civil administration purposes.
[[Image:Out of the way chapel - geograph.org.uk - 980382.jpg|thumb|240px|Hermon chapel, built in 1827 and rebuilt in 1906]]
The area of the parish is today largely mountain pasture. As with many such communities, its population has fallen over the years: in 1833 it had 164 inhabitants.<ref name=genuki>[http://www.genuki.org.uk/big/wal/DEN/LlanarmonMM/ Llanarmon Mynydd Mawr], [[GENUKI]]</ref> There are a number of rare late-medieval [[cruck]]-framed buildings.<ref name=cpat2>[http://www.cpat.org.uk/projects/longer/histland/tanat/1021.htm Tanat Valley Historic Landscape Characterisation], Clwyd-Powys Archaeological Trust</ref> There is also a Calvinistic Methodist chapel, Hermon, rebuilt in 1906 in a "curious" [[Art Nouveau]]-influenced style.<ref name=jones129>Jones, A. ''Welsh chapels'', National Museum of Wales, 1996, p.129</ref>