Holy Island has been continuously inhabited since the Neolithic period. The oldest evidence is a long house similar to those found in Scotland and elsewhere in the British Isles. Near this site stands the Bronze Age Ty Mawr standing stone, a monolith measuring nearly nine feet tall. But the most remarkable prehistoric remains are the Holyhead Mountain Hut Circles -- stone dwellings that were inhabited before the Iron Age and remained in use through the Roman period, with pottery finds dating from the 3rd to 4th centuries AD. Limpet shells found in the enclosure walls date to 200 BC. William Owen Stanley excavated the site in 1862, and the hut circles remain among the best-preserved prehistoric settlements in Wales. After the end of Roman rule, Irish settlers invaded Anglesey; Cadwallon Lawhir eventually defeated them on Holy Island itself, adding another layer to the island's already dense history.

The western side of the island is dominated by Holyhead Mountain, an area of maritime heather moor that rises to 722 feet -- the highest point in the county. It is not a mountain in any Alpine sense, but on a low-lying island exposed to the Irish Sea, it feels like one. North Stack and South Stack are two rocky islets just off the coast by the mountain. South Stack is connected to Holy Island by steep steps and a suspension bridge, providing access to the South Stack Lighthouse and an RSPB seabird reserve. The coastline is mostly rocky, though sandy beaches at Trearddur Bay and Penrhos Country Park break the pattern. The rocky shores have claimed many ships over the centuries -- the island's exposure to Atlantic weather makes its waters treacherous.

Holyhead, the largest town, is home to over 11,000 of the island's roughly 13,600 residents. Its defining feature is the Port of Holyhead, from which passenger and freight ferries cross to Dublin Port. Many visitors to Holy Island are simply passing through, waiting for a ferry. The largest hotels cluster near the A5 and A55 roads that carry traffic from the mainland across the Stanley Embankment, a causeway that also carries the North Wales Coast Line railway. There is a much older crossing too: Four Mile Bridge, the original link between Holy Island and Anglesey proper. Thomas Telford's road, Robert Stephenson's railway, and the modern dual carriageway have each reinforced the island's role as the point where Britain reaches toward Ireland.

Holy Island shares Anglesey's distinction as one of the Welsh language's strongholds. The county has the second-highest percentage of Welsh speakers in Wales, at over 57 percent. The secondary school, Ysgol Uwchradd Caergybi, claims to have been the first comprehensive school in England and Wales. Around 30 miles of the 125-mile Anglesey Coastal Path crosses Holy Island, winding past the hut circles, the lighthouse, and the mountain. Walking it, you pass through landscapes that have been continuously occupied for five millennia and continuously argued over for nearly as long. The standing stones, the saint's chapel, the ferry terminal -- Holy Island layers its eras without apology, each one visible beside the next.