5 Best Sights in Wales

The last abbey of the Cistercian order to be founded in Wales, Valle Crucis was built in 1201 and abandoned in 1537—a victim of Henry VIII's violent dissolution of the monasteries. Today it's a highly picturesque ruin beside a glassy lake. Surprisingly large sections survive relatively intact—particularly the sacristy and more or less complete chapter house, with its intricate vaulted ceiling. In its day Valle Crucis was one of the richest and most powerful abbeys in Wales; despite half a millennium of decay, this is still an impressive site to wander. It's currently only open for guided visits.

The British writer Caitlin Moran once wrote fondly of Aberystwyth's "Glitter-glue sea and smashed-cake castle," and these crumbling ruins at the southern end of the bay do have an endearing quality. Built in 1277, the castle was one of the key strongholds captured in the early 15th century by Owain Glyndwr, a Welsh prince who led the country's last serious bid for independence from England. Today it's a romantic, windswept ruin, rather incongruously used as a cut-through walking path by locals for whom it's nothing out of the ordinary at all. To find the ruins, just walk along the bay, away from the town center; they are located just after the pier.

Built in the 12th century, this abbey was, in its day, one of the largest and most important in the British Isles. Though just a shell, the main church gives an impressive sense of scale, with its tall buttresses and soaring, glassless windows. Here and there small sections of the original building have survived unscathed, including an undercroft with a vaulted stone ceiling. Neath Abbey is 9 miles northeast of Swansea.

Remote, atmospheric, and astoundingly little-known, Tre'r Ceiri is one of the most impressive ancient monuments in Wales. Today parts of the 4th-century fort's outer walls are still intact (rising more than 18 feet in places), and within are the ruins of 150 stone huts. They were inhabited by a Celtic tribe known as the Ordovices, and may have survived as a settlement for up to 700 years. From Porthmadog, take the A497 west, then turn left onto the A499 just before Pwllheli. At the village of Llanaelhaearn, turn left onto the B4417. Less than a mile down this road is an unmarked footpath on the right leading straight up a hill to Tre'r Ceiri.

One of only three walled Roman forts in Europe, this small 3rd-century structure with three walls and towers overlooks Holyhead's harbor and watched for Irish raiders until abandoned at the fall of the empire. The church of St. Cybi, now inhabiting the interior grounds, dates mainly to the 16th century. Heavily damaged by Oliver Cromwell's soldiers during the English civil wars, it was restored in the mid-19th-century and houses impressive Carrara marble statues and stained-glass windows. A second church on the south end was converted into a school for poor children in the 1700s.