The Mackenzie Building, Old Assembly Close, 172 High Street, Edinburgh

The Mackenzie Building, located at Old Assembly Close, 172 High Street in Edinburgh, was designed by Alexander Black between 1839 and 1840, with later additions and alterations. This two-storey and attic building features a Scots Jacobean style and a mansard roof, along with a tall corbelled stack at the east gable. It is situated on sloping ground at the rear of 172 High Street and is constructed of ashlar stone, featuring a string course between the ground and first floors, an eaves cornice, and buckle-quoins. The parapet has segmental-arch details, and there are three segmental-arched dormers on the north and south elevations.

The entrance elevation, which faces north, has four bays and includes a central projecting pilastered and pedimented timber porch with a timber doorpiece positioned between the two storeys. There is also an ogee-roofed entrance pavilion at the northeast corner that leads to a courtyard and a stepped platt.

The rear wing, which is two-storey and attic with five bays, is built over a raised basement and is integrated into the sloping ground. It features a door on the east elevation with a Jacobean style panel above and a further pedimented entranceway that abuts the southeast corner boundary wall.

The building predominantly has 12-pane timber sash and case windows, a Scottish slate roof, particularly broad axial ashlar stacks, clay cans, and cast-iron rainwater goods. The interior was partly observed in 2007 and has been extensively refurbished for use as Parliament Offices.