||Buildings of greatest importance to Northern Ireland including both outstanding architectural set-pieces and the least altered examples of each representative style, period and grouping.
||Buildings which might have merited grade A status but for detracting features such as an incomplete design, lower quality additions or alterations. Also included are buildings that because of exceptional features, interiors or environmental qualities are clearly above the general standard set by grade B buildings. A building may merit listing as grade B+ where its historic importance is greater than a similar building listed as grade B.
||Buildings of local importance and good examples of a particular period or style. A degree of alteration or imperfection of design may be acceptable.
The organization of the lists in this series is on the same basis as the statutory register. The county names are those used in the register, which in the case of Northern Ireland means the province's six traditional counties.