18 Castle Street

18 Castle Street is a block of four houses, built in the 18th century. The building stands three storeys tall with a slate roof and features a curved corner bay at the western end. The façade facing the street has a total of eight windows, including the corner bay. The exterior is finished with render and pebbledash that is incised to resemble masonry, and it is accented by giant pilasters at both ends, along with bands at the second floor level and at the first floor sill level.

On the second floor, there are small square sash windows, while the first floor has tall transomed casement windows. Each house on the ground floor has either a single or triple sash window without glazing bars, except for No 18 on the west, which has two sash windows. The eastern house, No 21, features a corner bay and has two doorways. The western end of the building, where Berkeley Place once stood, has been rebuilt in a Georgian style, presenting a three-window elevation with a pedimental gable, end pilasters, and banding between the floors.