Skylon (Festival of Britain)
The Skylon was a futuristic-looking, slender, vertical, cigar-shaped steel tensegrity structure located by the Thames in London, that gave the illusion of floating above the ground, built in 1951 for the Festival of Britain. A popular joke of the period was that, like the British economy of 1951, "It had no visible means of support".
Source: Wikipedia — Skylon (Festival of Britain) (CC BY-SA 4.0)