It is located at the eastern entrance to the Menai Strait, the tidal waterway separating Anglesey from the coast of North Wales.

Beaumaris was originally a Viking settlement known as Porth y Wygyr ("Port of the Vikings"),[3] but the town itself began its development in 1295 when Edward I of England, having conquered Wales, commissioned the building of Beaumaris Castle as part of a chain of fortifications around the North Wales coast (others include Conwy, Caernarfon and Harlech).

[5] The ancient village of Llanfaes, a mile to the north of Beaumaris, had been occupied by Anglo-Saxons in 818[citation needed] but had been regained by Merfyn Frych, King of Gwynedd, and remained a vital strategic settlement.

To counter further Welsh uprisings, and to ensure control of the Menai Strait, Edward I chose the flat coastal plain as the place to build Beaumaris Castle.

The 'troublesome' residents of Llanfaes were removed en bloc to Rhosyr in the west of Anglesey, a new settlement King Edward entitled "Newborough".

[10] From 1562 until the Reform Act 1832, the Beaumaris constituency was a rotten borough with the member of parliament elected by the corporation of the town, which was in the control of the Bulkeley family.

One of the last prisoners to hang at Beaumaris issued a curse before he died – decreeing that if he was innocent the four faces of the church clock would never show the same time.

[14] Beaumaris was a haven of refuge in a storm to the passengers of the sailing ship, Everton, on a Thursday morning in November,1762 when it ran aground on a nearby sand bank.

The ship's Captain, knowing nothing could be done before high tide six hours hence, ordered the yawl to be lowered carrying himself and all the passengers to shore for fresh provisions in the town.

The high mountain of Penmanmaur, lying over against the town, with the top in the clouds, and all the visible parts covered with snow, exhibited the most grand and majestic appearance, I had ever seen.

"[15] According to historian Hywel Teifi Edwards, when the "Provincial Eisteddfod" was held at Beaumaris in 1832, a young Princess Victoria and her mother were in attendance.

[21][22] Notable buildings in the town include the castle, a courthouse built in 1614, the 14th-century St Mary's and St Nicholas's Church, Beaumaris Gaol,[23] the 14th-century Tudor Rose (one of the oldest original timber-framed buildings in Britain) and the Bulls Head Inn, built in 1472, which General Thomas Mytton made his headquarters during the "Siege of Beaumaris" during the second English Civil War in 1648.

[28] After the war, the company focused on their ship building produced at the site with fast patrol boats, minesweepers and an experimental Austin Float Plane.