St Michael and All Angels stands outside the village of Castlemartin, adjacent to two holy wells which may indicate the site held religious significance in pre-historic times. A cross, dating from the 7th–9th centuries, was discovered embedded in the church wall in 1922, but has subsequently been lost. The main body of the current building dates from the 13th century, although the centrally-placed tower is later, of the 14th or 15th centuries. The church was restored, firstly in the early 19th century, and again in 1858.
The church has some notable Victorian stained glass from the studios of Hardman & Co. and Heaton, Butler and Bayne. A Hardman window of the Crucifixion, to a design by Augustus Pugin, has been described as the best example of Pugin's work of any church in Wales. The church contains a First World War memorial commemorating three men from Castlemartin who were killed in the conflict. The church was declared redundant in the early 21st century and is now in the care of the Friends of Friendless Churches.
St Michael's is a Grade I listed building. The adjacent vicarage, now derelict, and a mounting block in the churchyard have their own listings.
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The Church of St Donatus name refers to Donatus of Zadar, who began construction on this church in the 9th century and ended it on the northeastern part of the Roman forum. It is the largest Pre-Romanesque building in Croatia.
The beginning of the building of the church was placed to the second half of the 8th century, and it is supposed to have been completed in the 9th century. The Zadar bishop and diplomat Donat (8th and 9th centuries) is credited with the building of the church. He led the representations of the Dalmatian cities to Constantinople and Charles the Great, which is why this church bears slight resemblance to Charlemagne's court chapels, especially the one in Aachen, and also to the Basilica of San Vitale in Ravenna. It belongs to the Pre-Romanesque architectural period.
The circular church, formerly domed, is 27 m high and is characterised by simplicity and technical primitivism.