The Upper Monks' Garden at Skellig Michael is not a garden in any soft or domestic sense. It is a narrow platform of reclaimed ground, roughly seventy metres long and only eight metres wide, carved into the steep island face and held in place by a system of dry-stone retaining walls that have survived, with some repair, for over a millennium.

The terrace is defined on its north-western side by the revetment wall of the main terrace, a revetment being a facing of stone built to hold back earth or rubble and prevent collapse. A substantial curving retaining wall bounds the south-eastern edge, sweeping around to enclose the south-western end where it meets the north-western wall. At the north-eastern end, a shorter retaining wall separates this upper terrace from the Lower Monks' Garden below. The result is a self-contained pocket of workable ground, almost entirely engineered, on a surface that offered the monks no natural soil to speak of. Whatever was grown here, compost and organic matter would have been laboriously accumulated over years, perhaps generations, to create anything approaching cultivable earth.