One of several churches in this part of Powys dedicated to St Michael, the archangel who threw Satan out of Heaven. (Llanfihangel Nant Melan is another.) The St Michael's Churches Trail is a car-based trail which takes you round them all.
Llanfihangel Rhydieithon church has a very early font (Norman or even earlier), a peal of six bells and an impressive organ bought from the larger church at Bugeildy when they were upgrading. It had just been installed when we walked past the church on the 1998 round-Wales pilgrimage and the organist was trying it out so we had a free recital.
Accommodation in the area: you could try the farms in the Graig Farm Organics group.