The new TV mast at Emley Moor was taking shape and by June 1970 was already 625ft tall.
It measured 90ft across the base and used 16,000 tons of concrete and 1,500 tons of steel. It had a central mast of 200 tons and a 54-ton aerial, which would eventually take its height to 1,100ft.
At the time, this made it the third tallest structure in the world and the tallest aerial above sea level.
Even today, it is still the tallest free-standing structure in the UK, the 4th tallest tower in the EU and the 24th in the world. It has been a Grade II listed building since 2002.
It is the third structure to be built on the site, the original being a lattice tower, which was put up in 1956, after which a replacement mast was erected in 1966. This second mast collapsed in 1969 under the weight of snow and ice which formed upon it, coupled with high winds.
The present mast was built to withstand the high winds and when you are at the top, you can feel the entire structure swaying gently on windy days. Maintenance on the mast is due to take place later this year.