4, South Quay

4 South Quay is a house, now a museum, dating back to 1596. Originally built as a smaller house for Benjamin Cooper, it was expanded between 1603 and 1610 into a courtyard house alongside number 3. The building underwent alterations in the 18th century, was refronted in the early 19th century, and restored in 1833. The facade is of gault brick, while the rest of the building is red brick. It has pantiled roofs.

The exterior presents a two-and-a-half-story facade arranged in a six-window range. A panelled door is set beneath an overlight, sheltered by a porch supported on Roman Doric columns. The windows are six-over-six sash windows with gauged skewback arches. Blind windows were added to the top floor in 1809, and first-floor windows have iron balconies. A gabled roof has a ridge stack to the left of centre. A round arch on the right leads to Row 83. The south return, along Row 83, is two stories with a dormer attic, built with red and yellow brick. The ground floor features a five-light mullioned window renewed in the 19th century alongside an early 17th-century six-light ovolo-moulded mullioned window with a central king mullion. An arched window illuminates the staircase. The east gable was rebuilt by the National Trust after 1943.

The interior entrance hall features panelling from around 1730. The south front room was subdivided in the 19th century but retains cruciform bridging beams with sunk-quadrant mouldings. The dining room to the north has small-framed panelling with reeded and fluted Ionic pilasters and an oak chimney-piece with a three-bay arcaded overmantel bearing the initials C over B A, standing for Benjamin and Anne Cooper. The storeroom to the east contains a single unfluted Ionic column, the sole remnant of a former open courtyard loggia. A staircase from 1809 has turned balusters, a ramped and wreathed handrail, and a late 18th-century Chinese-pattern dog gate. The kitchen in a rear wing has small-framed panelling; a C13 double trefoiled aumbry, likely from the Greyfriars, is set into the north wall. A courtyard window, matching the one on the ground floor, provides light. A rear kitchen to the east has sunk-quadrant bridging beams. The front drawing room on the first floor features continuous arcaded panelling with fluted pilasters. The chimney-piece incorporates two tiers of paired Corinthian columns framing three arcaded panels, with the Arms of James I in the centre. The plastered ceiling, dating back to approximately 1600, features high-relief ribs arranged in a square pattern with twisting sides and pendants, along with lower-relief vine decoration. A further room north of the drawing room features small-framed panelling and an early 17th-century chimney-piece. An upper rear corridor has two three-light C17 cross casements with roundels of painted Flemish glass dated 1612. The roof structure incorporates arched braces, two tiers of butt purlins, curved windbraces, and plain collars.