Incredible A road runs entire length of country - no one knows its start point

It's the only A road in the UK that runs the entire length of a country. It begins at a seaside location in the south and terminates at another in the north. At both ends, it could almost literally not be closer to the water.

And inbetween, this stunning route passes over and beside vast mountains, lakes and castles, and cuts through two national parks. But its starting point remains a mystery to many, including even those who live on it and the thousands that often walk on and by it on a sunny summer day.

For many, the mere mention of the A470 conjures up soul-destroying images of bumper-to-bumper traffic during peak commuting hours into or out of northern Cardiff from the south Wales valleys. But this "urban motorway" section is merely a small part of the road.

Heading north from there, the road winds through iconic Welsh towns such as Pontypridd and Merthyr, which were instrumental in Britain's industrial revolution when Welsh coal and iron were of global significance. Just beyond Merthyr, the road enters the Brecon Beacons (now officially known as Bannau Brycheiniog in Wales) and skirts Pen y Fan, the highest mountain in south Wales.

The views from your car at this juncture are breathtakingly beautiful, with heart-stopping drops from the road down a mountainside on one side and a wall of rock and tough hillside grass on the other.

North of the charming market town of Brecon, where you could stop to enjoy a couple of hours on a narrowboat on the Brecon and Monmouthshire Canal, the road takes you through the stunning rural mid Wales and the breathtaking Elan Valley. This little-known beauty spot rivals the Lake District with its picturesque scenery and lakes.

If hunger strikes, just north of Brecon, you'll find the Felin Fach Griffin, a cosy spot serving some of the finest food in Wales beside roaring log fires, with comfortable rooms for an overnight stay.

As you continue northwards, expect to encounter slow-moving farming vehicles as you are now in the heart of Welsh farming country. The Royal Welsh Show, a major event in the farming calendar, takes place over one week every summer near the town of Builth Wells.

Further north, the route takes you through the Coed y Brenin forest, which translates to Forest of Kings in Welsh, and the Eryri (formerly known as Snowdonia) national park. You'll pass not too far from Yr Wyddfa (or Snowdon), the highest mountain in all of Wales and England.

The A470 also goes through the historic slate mining town of Blaenau Ffestiniog, which was once a hub for slate exportation. The picturesque village of Betws-y-Coed, with its Alpine-like surroundings of waterfalls, woodlands and mountains, is another highlight along this route.

The Swallow Falls waterfall, located just outside the town, is a must-visit spot. The charming village of Beddgelert, known for its quaint stone cottages, pubs and one of Wales' most tragic tales, is also nearby - it ranks as one of the UK's most beautiful villages.

As you continue northwards, the road takes you close to Conwy, home to one of Wales' most magnificent castles, part of King Edward I's Ring of Steel. Overlooking the Conwy estuary, the castle remains a formidable structure even today.

Conwy itself is a delightful town, offering plenty of options for dining, drinking and overnight stays, as discovered by this writer. The A470 concludes at the renowned seafront promenade of Llandudno, a favourite staycation and day trip destination for Brits since the Victorian era.

Few realise this, but the A470 actually begins at Mermaid Quay in Cardiff Bay, a major tourist spot in the Welsh capital city just outside the Wales Millennium Centre. It stretches up Lloyd George Avenue before heading up Cardiff's North Road and morphing into what everyone in south Wales probably thinks of when someone says "A470": the dual carriageway running from Cardiff through the valleys.

The original road was constructed in 1922, stretching from Cardiff Docks to Brecon. The modern route is the result of a campaign in the 1970s by the Western Mail newspaper for a single route to link north and south Wales. At 186 miles long, it holds the title of Wales' longest road.

Simply put, when you have plenty of time to spare. Driving from one end to the other is a magnificent journey, with numerous spots to pause for delicious food, pleasant walks and breathtaking views. However, if you're pressed for time, try to avoid getting stuck in a Cardiff traffic jam or behind a tractor in mid Wales.

As for dining and accommodation options on the A470, there are plenty either directly on the road or just a short detour away. Consider stopping in the towns of Conwy or Brecon for lunch or dinner. One of the most delightful places to eat in all of Wales, the Felin Fach Griffin, is conveniently located by the side of the road.