Lon Union (A4085)
Winding south towards Beddgelert, the A4085 is a fiercely tight and twisting route. Despite being dual-track, the relentless frequency of corners makes it feel much narrower. It is an intense, busy road that demands constant line-choice and immediate responses, offering little in the way of resting periods.
The road runs immediately adjacent to the Welsh Highland Railway in places, and you'll frequently encounter slow-moving tourist traffic watching the trains.