The ruined remains of a building thought to have possibly served as a private chapel to St German's Cathedral,although this is not proven and the building had no architectural features of an ecclesiastical or datable character. The style of building and the height of the walls show it to have been an advance on early keeill-types with which it otherwise accords in its small size and plain rectangular form.


'St Patrick's Chapel' stands within the earthworks about the centre of the island. It is built of undressed, grey local stone with some red sandstone. The ruin is orientated east to west and its walls average up to 1 metre wide in thickness.  Internally, the building measures 6.8 metres by 3.6 metres. The majority of the walls stand to an internal height of 1.2 metres, though the east wall, which has a square window of 0.8 m sides, still stands to its original height. There is an entrance through the western wall.


A cross-slab, interpreted as an altar-slab (Manx Cross No 46) 'appears to have been from this Chapel' (Re-numbered No 67 but apparently is also alleged to have come from St Patrick's Church).