18-20 High Street, Omagh, Co. Tyrone, BT78 1BQ

A three-storey brick and stone former post office, built in 1905, located on the north side of High Street in Omagh. The building was designed by architect J. L. Donnelly and represents early twentieth-century classical styling in an urban setting, though historical records suggest construction dates vary between 1902 and 1905. It is now occupied by the Nationwide Building Society, having previously served as the Belfast Bank.

The building is rectangular on plan, three openings wide, and faces south with a central pedimented breakfront. It features a hipped natural slate roof with angled blue and black hip tiles and ogee-profile uPVC gutters. The principal elevation displays a strong polychromatic brick and limestone façade characteristic of Edwardian design. Walling is Flemish-bonded red brick over a splayed plinth with stone dressings. The ground floor is distinguished by banded rusticated stone, present on principal elevations only; other elevations are plain brick without ornamentation. A lower return extends to the rear, flanked to the left by a single-storey flat-roofed annex and to the right by a two-storey flat-roofed addition. A two-storey pitched-roofed extension extends to the rear of the return.

The principal south elevation features a central pedimented breakfront with dressed limestone quoins above the ground floor and a moulded entablature parapet coping. The ground floor has banded rustication over a chamfered plinth with a projecting moulded cornice over a frieze above; the windows are replacement teak casements, with the central window widened and covered by a plastic fascia. The first floor displays a moulded stone sill course over a dressed apron-level platband with moulded entablatures above. Square-headed painted timber 6/1 sashes are set within lugged moulded stone architraves with keyblocks; the breakfront has a central sash flanked by 4/1 sashes in a dressed limestone surround with keyblocks, with the central window surmounted by a segmental pediment on carved brackets. The second floor has diminished square-headed painted timber 6/1 sashes; the breakfront contains three windows with moulded architraves and shared sills. The prominent limestone triangular pediment features carved oak leaves as spandrel decoration and a central cartouche bearing the "E VII" (Edward VII) cipher encircled with the Order of the Garter, surmounted by a Tudor crown—a significant Edwardian marking of the building's date.

The west elevation has four casement windows on the second floor, with two windows each on the first and ground floors to the left side. The north (rear) elevation is largely abutted by the return; the exposed section contains a single horizontal casement window with security bars to the left. The return's rear elevation is abutted by the rear extension; the exposed section has a single sash window with security bars on the second floor, and the right cheek has two sash windows per floor. The left cheek is abutted by the two-storey addition with two exposed windows, while the extension rear gable is rendered and blank. The east elevation is abutted by a neighbouring building with a blank exposed section.

Historical records show the building first appeared on the third edition Ordnance Survey map of 1905–6, although an earlier building occupied the site according to the 1833 and 1854 maps. Valuation Revision records document the property as the "post office, Inland Revenue office and yard" with an 1905 entry noting a "site for new post office," valued at £85 with R. H. Ellis listed as the occupier. The upper floors underwent comprehensive remodelling circa 1960, which has compromised some original detailing, though the building remains a good example of early twentieth-century urban classical architecture.

The building fronts directly onto High Street, with a tarmac parking lot to the rear and a tarmac driveway to the west. It lies within a conservation area.