On this day in1991, the Warsaw radio mast, at one time the tallest construction ever built, collapsed.
The Warsaw Radio Mast was the world’s tallest structure from 1974 until its collapse on 8 August 1991.
It was the second tallest structure ever built, being surpassed as tallest by the Burj Khalifa, completed in 2010.
The mast, which was designed by Jan Polak, was 646.38 metres tall.
Its construction, started in July 1970, was completed on 18 May 1974, and its transmitter entered regular service on 22 July of that year.
Its base was 115.2 metres above sea level.
Because a voltage potential of 120 kV existed between the mast and ground, it stood on a 2-metre high insulator.
It operated as a mast radiator so its height was chosen in order to function as a half-wavelength antenna at its broadcasting frequency.
The signals from its 2 megawatt transmitters could be received across essentially the entire globe.
Its weight was debated: Polish sources claimed 420 tonnes.