Porth Mawr gateway, lodge, walls and railings at Llantarnam Abbey

The Porth Mawr gateway, lodge, walls, and railings form part of the estate of Llantarnam Abbey, dating from the 1830s. The imposing gateway is a large, square, battlemented gate tower constructed from Bath stone ashlar, with a low, single-storey lodge positioned to its left. The front of the gate tower is asymmetrical, featuring a large, segmental-pointed carriage arch to the right and a lower, narrow, segmental-pointed pedestrian entry to the left, both united by a shared hood mould. A diagonal two-step buttress is located at the left angle, while the right angle has an octagonal corner pier with a small loop facing forward. A string course runs beneath the battlements, extending around the right corner pier. The battlements themselves have moulded coping, and a large panel displays a carved shield above the main entry, with the battlements stepped above on either side. Carved scrolls are present on the battlements; the longer left scroll is inscribed "Porth Mawr," and the right scroll reads "1836." A smaller octagonal finial sits on the left, while a larger, taller octagonal finial with a brattished top and a carved stone eagle adorns the right. The right side of the tower is also battlemented, with two openings similar to the pedestrian gate (lacking hoodmoulds) and a large raking buttress positioned centrally, featuring a grotesque carving in the string course above. A diagonal buttress and a small octagonal finial are found at the right corner of the rear. The rear elevation features a section of the lodge covering the right side, positioning the carriage arch centrally. Battlements and small octagonal corner finials are visible here, along with a taller central battlement displaying a shield. Large timber gates are within the main arch, featuring spearhead cresting, a panelled lower third and open upper sections incorporating Gothic ironwork. Inside the porch, a ribbed vault with moulded ribs, fine carved head stops, and two arches to the right and two to the left lead to the pedestrian throughway. This throughway contains two ribbed vaults with carved head stops and leaf bosses, separated by a Tudor arch. The first bay has a square-headed, six-panel studded door, while the second has a two-light window, both set within chamfered surrounds.

The lodge to the left is L-shaped, and a short, low ashlar front wall includes a string course beneath a parapet. It features a shouldered, coped gable with an external chimney stack topped with a castigated terracotta pot. The slate roof covers a three-sided bay with small-paned square-headed windows on either side and a central door, all set in chamfered surrounds. A rear wing, facing the drive beyond the gate tower, has a similar parapet and a three-light mullion window with a deep hoodmould. A gable end incorporates two narrow single lights with deep hoodmoulds, supporting an ashlar oriel of 1-2-1 lights, featuring a curved moulded base and moulded coping. The gable above is stepped and topped with a finial. A sidewall ashlar chimney is also topped with a castigated terracotta pot. A 20th-century extension is attached.

The entrance walls and railings to the right of the gateway include a short ashlar wall pierced with three rectangular openings filled with scrolled iron inserts and incorporating a stone seat. Serpentine-curved ashlar low walls with ornate iron low rails (featuring scrollwork and quatrefoils between alternate spearhead and fleur-de-lys headed uprights) extend from the right end of this wall and the left corner of the gate tower. The outer walls are defined by tooled purple sandstone piers with octagonal, curved caps.