The parish church of St. Nicholas Without occupied, for much of the medieval period, a portion of another, far grander structure. Specifically, the north aisle and transept of St. Patrick's Cathedral were physically walled off and pressed into service as a separate parish church, a pragmatic division that effectively created two distinct ecclesiastical spaces within a single architectural shell.

The name "Without" signals something important about its status: it refers to the church's position outside, or beyond, the old city walls, which placed it in a jurisdictional and topographical category distinct from parishes contained within Dublin's medieval core. According to research compiled by Geraldine Stout and drawing on the work of Bradley and King (1987) and Clarke (2002), the church was situated to the west of St. Patrick's Cathedral. The FMD map of 1978 places it at grid reference F14, which gives some sense of how carefully its location has been reconstructed by scholars working from historical cartography rather than surviving fabric.

There is no standing building to visit today. The church's long dependence on borrowed space within St. Patrick's, and the subsequent erasure of its physical presence from the streetscape, means the site survives primarily as a mapped coordinate and a footnote in the history of Dublin's medieval parish organisation. St. Patrick's Cathedral itself remains open to visitors and retains much of its medieval structure, so those interested in the arrangement that once divided the building can at least stand within the north aisle and consider how a simple wall, now long gone, once defined the boundary between two separate congregational worlds. The cathedral's own interpretive materials may not address St. Nicholas Without directly, so it is worth approaching the visit with some background reading already in hand.