20 Wellington Square, Ayr

20 Wellington Square is an early 19th century, 2-storey house with a basement and attic, featuring a classical design and forming part of a terrace. The exterior is finished in painted harl and includes a ground floor band course, eaves course, cornice, blocking course, and strip quoin on the outer right side. The window openings have painted margins.

On the north elevation, there is a central stepped platt that oversails the basement, topped by a corniced, block-pedimented columnar doorpiece with a 2-leaf timber door. Above this, there is a single window aligned at the first floor. Boarded timber doors are located at the right and left re-entrant angles of the basement below. The fenestration is regular across the basement, ground, and first floors in the flanking bays. The attic features two piended dormers at the outer right and left.

The windows at the ground and first floors are 12-pane timber sash and case, while the basement has plate glass and the attic has 16-pane windows, along with a rooflight. The roof is covered in grey slate and has coped stacks with circular cans.

The interior was not seen in 1998.