Three of its four walls are now entirely buried beneath centuries of accumulated soil, leaving only the western façade exposed. Step inside, however, and the walls reappear, neatly constructed from horizontally laid rectangular slabs, bowing inward slightly under the pressure of the earth pressing against them from outside. The building measures just 2.5 metres north to south and 3.7 metres east to west internally, making it one of the more diminutive ecclesiastical structures in Ireland. Entry is through a trabeate doorway, meaning one roofed by a single flat lintel slab rather than an arch, just over a metre high and narrowing slightly towards the top. Stone projections on either side of the interior doorway once held the posts of a timber door; one survives intact, the other is broken.

The island's monastic tradition is attributed to St Brendan the Navigator, the sixth-century figure associated with a legendary sea voyage across the Atlantic, who is said to have founded a hermitage here. The church known as St Brendan's Chapel is the oldest and smallest of three churches on the site; the others, Templenafear (the Men's church) and Templenaman (the Women's church), stand a few metres to the south and south-west respectively. Inside the chapel, a low flat-topped drystone bench runs along much of the southern wall, strewn with loose, moss-covered stones. For much of its history, the church also contained a medieval wooden statue of St Brendan, which stood in the north-east corner and was an object of veneration for pilgrims who came to the island. When the antiquarian John O'Donovan visited in 1838, he found it already badly weathered, the face nearly effaced and the hands, carved in a gesture of thanksgiving, almost worn away. He recorded a local belief that anyone who lifted the figure three times in the name of the Trinity would receive the power to ease a woman's labour by touch. O'Donovan also noted the statue's close resemblance to a carved oak figure of St Molaise, dating from the late thirteenth or early fourteenth century, that had been kept in a church on the island of Inishmurray and is now held in the National Museum of Ireland. The Inishglora statue did not survive into the twentieth century, and had disappeared or decayed away entirely by the time later visitors came looking for it.