Blackwall Tunnel Ventilation Towers, London
1961-1962

The Blackwall Tunnel Ventilation Towers, designed in 1961-62 by Terry Farrell while he was employed at the London County Council's Department of Architecture, stand on each bank of the River Thames. The scheme comprised the ventilation buildings to the new Thames tunnel, and offices and workshops for the superintendent supervising tunnel entrances and the cladding selection for the tunnel linings. The towers on the south bank now stand within the Millennium Dome.

Each group of towers consists of two distinct elliptical plans that taper upwards and intersect to form a valley before separating into two funnels. The exhaust shaft is 27 metres (90 feet) high, while the inlet shaft is 12 metres (40 feet) high. Below the valley, the towers spread out to enclose four large circular fans and motors.

The buildings' distinctive form derives from their sprayed concrete (gunite) shells supported on stressed cables from a reinforced-concrete slab, over perimeter walls of blue brick and glass. The shell roof is supported from the slab, which contains instruments that measure air pollution. The concrete grillage holding this includes a spiral stair and a crawl-away ducting system linking the electrical installation to the motors from the switch room and transformers, and contains an airlock access to the tunnel below. The shells, coated with bitumen and cement paint to prevent corrosion, represented an early use of gunite as a building material rather than a repair material – chosen because it reduced the need for expensive shuttering

.The towers' curved form was inspired by Oscar Niemeyer's work at Brasilia, then appearing for the first time in the architectural press. Terry Farrell compares the romantic structure of the industrial buildings with the machine 'techno aesthetic' subsequently adopted for housing and office buildings in the neighbouring Poplar area of east London – the curved form of the two ventilation towers makes a strong contrast with the nearby Reuters headquarters building by Richard Rogers, the Robin Hood Gardens estate by Alison and Peter Smithson, and the Balfron Tower flats by Erno Goldfinger.

The towers were Grade II listed in 2000. The southern tower will eventually sit within a regeneration scheme by Terry Farrell & Partners that will create a new urban quarter for north Greenwich.