Remaining nave and crypt of 12th century cathedral and 13th century Presmonstratensian priory, both altered at intervals over subsequent cventuries.
NAVE: whinstone rubble with sandstone ashlar dressings and squared and snecked sandstone 15th century work (E of S wall). Rectangular-plan roofless structure incorporating 12th century fragements on N and S side walls to E. Break skewputts and cornice.
S WALL: 13th century round-arched Romanesque doorway (moved from former cathedral crossing) to W end, deeply chamfered reveals, nook-shafts with carved capitals, carved impost band and zig-zag detailing to arches above; line of later gabled porch regrettably incised across archway; high lancet flanking to right. Modern set-off buttress dividing these from 5 bays to right, largely 15th century with 3 former 2-light windows cut-down in 17th century, and further 13th century door ot outer right bay (now blocked as window) and with deeply moulded circa 1500 surround to exterior including hoodmould with finials bearing shield of Bishop George Vaus (1492-1508).
W ELEVATION: largely dating from 18th century rebuilding after collapse of early 17th century tower and shortening of length of nave. Former gallery lit by lancet extended down as doorway formerly with forestair, and with square window below.
E ELEVATION: circa 1610, with cill course below pointed arch window, serving as lintel course to 18th century door inserted below
N ELEVATION: blank; formerly abutted by cloister garth, with remaining evidence of former cills to windows above, redundant when roof lowered. INTERIOR: 4 wall tomb recesses - 1 12th century to E altered by insertion of door, and 2 13th century to E end of N wall with cusping and decorative carving 1 round arched recess of 17th century in centre of N wall. Various wall monuments.
CRYPTS: remains of 2 13th century and 1 14th century crypts to extreme E (beyond advanced altar), with outline of former chapels above ground outlined by William Galloway, architect Whithorn, for 3rd Marquess of Bute in lat 19th century. Pointed barrel-vaulted crypts entered from S, through western vault, lit from E. 15th century door leads between this and eastern vault (formerly accessed by stairs from church, of which lower treads remain). Further door in N wall.