The site of a medieval chapel of ease dedicated to St Thomas formerly located in the area now occupied by Swansea Docks.
Fourteenth century sources place the chapel as early as 1320. Saxton's map of 1610 does not show it suggsting the chapel had by then gone out of use. Isaac Hamon's description of 1690 refers to a building 'formerly a chapell of ease' implying an extant structure no longer in its original use. Eighteenth century estate maps of Dan-y-graig-fawr farm show 'the old chapel now in ruins' just above high water mark in a strip of land between the fields and the sea. Nineteenth century development work for the docks saw the chapel remains accidentally rediscovered and then finally destroyed.
The economic decline of Swansea in the sixteenth century, with some churches falling into disuse, and climate change leading to increased storminess, coastal erosion and sand encroachment, are likely contexts for the demise of the chapel.

A.Dulley 'The medieval chapel of St Thomas, Swansea', Gower 61 (2010), 44-50.