London Eye, London

The London Eye is the cantilevered observation wheel rising beside County Hall on the South Bank of the Thames. Its structure reaches 135 metres, while the wheel itself measures 120 metres across. Marks Barfield designed it.

The wheel is held by tensioned steel cables and supported by an A-frame on a single side, giving this huge structure the character of a spoked wheel suspended in the air. Look at the rim and its radiating cables: they make the engineering visible rather than hiding it inside a solid mass. The project was assembled in sections on platforms in the river, with those sections brought along the Thames by barge.

Once complete, the wheel was raised from a flat position into its upright form using a strand-jack system. It formally opened on 31 December 1999, and the public began riding it in 2000. Originally called the Millennium Wheel, it has carried more than 85 million passengers by 2025. From this riverside view, the striking detail is its unusual support: the vast circle seems to lean out over London while an A-frame carries it from a single side.