Its first section opened in 1973, and the rest was all built, but the A41(M) doesn't exist. It was canned in favour of orbital roadbuilding, and later resurrected in a more modest form.
The A465 Heads of the Valleys Road is one of the most spectacular trunk roads in the UK, and building it required some of the most remarkable civil engineering. This is the story of how the road was built in the 1960s, and how it's being rebuilt today.