The village lies at an important crossing point on the River Wye, connecting the historic counties of Brecknockshire and Radnorshire, and is located just outside the Brecon Beacons National Park, north of the Black Mountains.

[citation needed] The early village grew north of the river crossing, where a church was built dedicated to St Cynidr, a 6th-century bishop said to be buried in Glasbury.

[3] In the mid 11th century, the Welsh kingdoms (including Brycheiniog) were temporarily united under Gruffydd ap Llywelyn, King of Wales.

[4] After the Norman invasion, the kingdom of Brycheiniog (including Glasbury) was conquered or otherwise acquired by Bernard de Neufmarché, one of the Marcher Lords.

[6] In 1144, as part of an exchange, the lordship of the Manor of Glasbury passed from Gloucester Abbey to Walter de Clifford,[7] after which time it was frequently contested by the marcher families.

[9] In 1404, King Henry IV granted the lordship to Sir Robert Whitney "in consequence of his father...having been killed in the royal service and his property burnt by the Welsh rebels".

In August 1233, the castle was attacked and captured by King Henry III following a baronial rebellion by the Cliffords, but little more is recorded after that, though it was still in existence in a survey of Glasbury Manor dated 1561[6] Remains of its earthworks were visible near the centre of the village until housing development in the 1970s.

[13] In 1883, a second church was built north of the river and the Radnorshire side of the village transferred to the new parish of Glasbury, All Saints.

[6] The Old Vicarage, overlooking the river just to the south of Glasbury Bridge, is a hall house dating from the 15th century, and a Grade I listed building.

[14] Maesllwch Castle, overlooking Glasbury to the north, was built close to an original hall house of the Vaughan family which was later owned by Charles Lloyd.

The current building was grandly conceived in castellated style by the architect Robert Lugar for the de Winton family in the mid-nineteenth century.

Part of the castle was later demolished to reduce the costs of upkeep, but it remains an imposing private residence and a Grade II listed building.

[16] The Methodist chapel at Cwmbach in the north of the village dates from 1818, when local farmer Richard Hergest received a revelation that it should be built in his meadow.

In 1843 a royal commission of inquiry took evidence that "The Glasbury gates are a great inconvenience" since "persons travelling from one part of the village to the other pay two tolls", one to the Radnorshire and one to the Brecknockshire trust.

Foyles of Glasbury (formerly the Maesllwch Arms) in the northern half of the village is an old coaching inn with stables and is a Grade II listed building.

Since 2007, Glasbury has hosted an annual autumn to spring festival of events and workshops, celebrating literature, theatre, music and the visual arts.

Guests have included harpist Catrin Finch, singers Coope Boyes and Simpson, Kiki Dee, Julie Felix, John Kirkpatrick, Isla St Clair and local writer Jenny Valentine.

John Hughes, curate of Glasbury, was described as "an active and zealous orchard-planter" who "introduced grafts from vigorous-bearing trees of the choicest cyder sorts".

The area known as "Kilvert country" includes Glasbury and Hay-on-Wye, Clyro, Capel-y-ffin, Llowes, Llanigon, Painscastle, Clifford and Whitney-on-Wye.