St Peter's is the main parish church of Barnstaple, a large medieval building in the centre of the old town. Its most distinctive feature is the lead-sheathed spire, which has a pronounced twist and lean that is visible from a considerable distance. The twist is not structural damage but rather the result of the lead warping in heat and cold over centuries. It gives the church a slightly eccentric appearance that most people find charming.
The interior is large and contains a number of notable monuments, including brasses and carved memorial slabs to prominent Barnstaple families from the medieval and early modern periods. The churchyard is the resting place of several figures of local historical significance. The church is usually open during daylight hours. The tower and spire are best seen from Castle Street to the north, where they appear framed between old buildings.