Great Castle House

Great Castle House

A Grade I listed building constructed in old red sandstone ashlar with extensive patching, probably originally rendered and limewashed. The roof is of old tile with stone and brick chimneys. Although the architectural vocabulary reflects the spirit of an earlier age, the building represents a fine symmetrical design that is more Jacobean than Carolean in character, with only the slightest influence of classicism.

The main building comprises three storeys, an attic and cellar. It was formerly free-standing in a semi-H-shaped plan harking back to around 1600, with five bays arranged 1+3+1, the outer bays being wider and projecting slightly as wings. This arrangement should be compared with the contemporary but considerably more sophisticated Tredegar House. Wings were added around 1863. A plinth marks the ground floor level. Heavy moulded string courses run above the windows, which are of 3-lights in the outer bays and 2-lights in the centre, with transoms on the ground and first floors. The focal point is a central feature rising through the ground and first floors, framing the entrance door and first-floor windows. This consists of pairs of slightly projecting columns, partially fluted on the first floor, supporting a central spoked lunette inscribed with the date 1673. Ribbed double doors with a 19th-century lamp occupy the centre, accessed by steps leading up to the entrance. The first-floor central window appears to have been altered, though its original form is uncertain. The second floor is lower with smaller windows. All windows feature lattice glazed casements except the basement windows, where only the fixed top portions rise above ground level. Heavy coved eaves cornice and hipped roof with three hipped dormers containing casements. Tall brick stacks stand at each end.

The flanking early 20th-century wings differ from but closely match each other. The left wing is of two storeys; the right wing of one storey and basement. Both feature coved eaves cornices, tile roofs and mullioned and transomed windows. The left wing has five bays with the first set forward, two arched doorways with voussoired surrounds, a strong string course between floors and two brick stacks. The right wing is in five straight bays with a door on the upper floor in bay four, no string course and a brick stack. The return elevation shows a 3-light window below and a 2 and a 3-light mullion-and-transom window above. The rear elevation is more extensively altered with partly glazed additions, though the projecting stair wing remains visible.

The interior contains a large central hall with rooms on either side and a staircase in a tower behind. Cast iron Doric columns were added to the hall as support in the early 19th century. The ceiling is compartmented. Early 18th-century panelling and joinery date from alterations around 1700 when the Assize Courts were introduced. The elaborate chimneypiece with plaster overmantel and swags dates to 1673. The room on the right (now the CO's office) contains elaborate moulded panelling appearing 17th-century in character, though it does not fit properly against the cornice. The plasterwork and fine ceiling date to 1673. The room on the left (Adjutant's Office) is very plain by comparison. The main dog-leg staircase features widely spaced twisted balusters, a closed string, panelled newel posts with ball finials and a moulded handrail, with similar details repeated on the wall side. The staircase rises to the attic with plainer balusters on the top flight. A secondary narrower staircase, accessed through a studded iron door and rising only to the first floor, has a similar character and details.

The first floor is now a single large room formerly used as the Assize Court, although clearly divided originally into five rooms with the Criminal and Civil courts meeting together in one space. The original arrangement comprised a large central room with smaller rooms front and rear in either wing. The present room contains five distinct plaster ceilings of differing character: some are heavily and exuberantly moulded with wreaths, fruit, figures, circles and ovals, executed with daring undercuts and projection. All these ceilings date to 1673, whereas the panelling and fireplaces are around 1700, a discrepancy clearly visible where the panelling does not fit properly against the cornices. Two fireplaces feature bolection mould surrounds, one in speckled grey marble. This remarkable room now serves as the Regimental Officers' Mess. The upper floor contains plain office conversions. The attic reveals roof construction with considerable alterations and timber replacement, including large 20th-century timber reinforcement, though principals and many rafters date to the 17th century. An extensive vaulted basement lies beneath.

The interiors of the added wings are both altered and utilitarian but continue some of their original uses, particularly the Quartermaster's Stores in the right wing. The left wing houses the Museum of the Royal Monmouthshire Royal Engineers on the ground floor with offices above.