Designed landscape features are precisely that: elements introduced into the land not by agriculture or accident but by intention, usually as part of the broader fashioning of an estate or demesne, whether as ornamental planting, a ha-ha, a viewing mound, or some other deliberate shaping of the terrain to produce a particular effect.

Beyond the name of the townland and the county, the available record on this particular site is sparse, which is itself a kind of information. Features of this sort were often created for landowners who wished to impose an aesthetic order on their property, and many were modest enough, or rural enough, that they escaped the documentation lavished on grander demesnes. An Tamhnach Mhór, whose Irish name suggests a large cultivated field or clearing, sits in a part of Connacht where the landscape has layers of occupation and improvement running beneath the surface.