Alpha Tower

Alpha Tower is a twenty-eight-storey office block designed by George Marsh of Richard Seifert & Partners and built between 1970 and 1972, with construction engineering by Oscar Faber & Partners.

The building has a reinforced concrete frame with floor plates cantilevered from a structural core. The curtain walling comprises pre-cast concrete panels with bronzed aluminium windows with tapered sides. The ground-floor walling and piloti are finished with white, square tesserae.

The plan is cranked in shape, with wedge-shaped ends to the south-east and north-west. When viewed from above, the building outline resembles a boomerang. This cranked shape is replicated in the central service core, which houses lifts and services, with staircases positioned at the wedge-shaped ends.

At ground-floor level, the building is supported by a series of tapered pillars that grow thinner towards the bottom on their outward side and thinner towards the top on their inner side, with their flanks moulded with a gradual curve to accommodate this change. The lintels above the pillars are angled. At the south-eastern end, the curtain wall corner is cut away at an angle, while at the north-western end it drops down to the level of the surrounding podium, both angles indicating the staircases housed at these locations. The ground-floor walling is covered with white mosaic tesserae.

Above ground floor, the cladding comprises striated pre-cast concrete panels. All window openings are divided by tapered mullions. From the second-floor level upwards, the mullions have an angled splay at their base where a ventilation grille is positioned. Window surrounds are of bronzed aluminium. The wedge shapes at the north-western and south-eastern ends have blank walling either side of a vertical channel rising for the full height of the building at the corner. Service rooms for air conditioning plant are set back from the edge at the top of the building.

The reception area is positioned at the south-eastern end and has plate-glass windows providing views across the building, creating an impression of transparency. Plant and storage areas occupy the north-western end of the ground floor. The central service core rises through all floors, mirroring the curved shape of the building, with lifts to either side. The window mullions are vertical to their inner edges but tapered at either side of the window opening, with curved reveals to accommodate this change. Dogleg staircases are set at the sharp ends of the floors. They do not extend fully into the corners, but each has a continuous, canted bay looking out through the vertical slit at the building corner. A spiral staircase has been cut through the flooring to connect the twentieth and twenty-first floors. Floor plans have been adapted at various dates and vary between open-plan and temporary office divisions.

To the west of the office block, free-standing in the paved plaza surrounding it, is a low service block. This is covered in white tesserae and consists of two circular turrets, obliquely cut at their tops, and a square block with rounded corners, also cut at an oblique angle to its top. These clustered shapes house various functions associated with servicing the office tower and the former ATV studios.

The internal floor space at each level of the office block is not included in the statutory listing, with the exception of the external walls, including the piers positioned between windows and the window embrasures to their full internal depth; the lift lobby at the centre of each floor, except the lifts themselves; and the service stairs at the northern and southern ends of each floor. For the service block, the outer walling and roofs are included within the statutory listing, but the internal space is not.