At the eastern edge of the village, in a privately owned field opposite Black Rock Road, very near to the Leechpool turn, is evidence of a significant neolithic chambered tomb or long barrow.

[2] The stones can be reached by following the public footpath accessed via the kissing gate which is situated on the left[3] about 150 metres (160 yd) from the main road toward Leechpool.

In his 1954 Monmouthshire Sketch Book Hando writes: "Garn Llwyd, Gwern-y-Cleppa and Heston Brake are our three outstanding dolmens".

According to tradition, in about the 6th century Caradog Freichfras, king of Gwent, moved his llys or court from Caerwent to Portskewett, where there was a strongly flowing fresh water spring which only dried up later when the Severn Tunnel was built.

Archaeological investigations have revealed wetland structures, including fish traps, with dates from the 6th century onwards.

According to the Anglo-Saxon Chronicle, in 1065 Earl Harold of Wessex, having defeated Gruffydd ap Llywelyn and conquered areas around Hereford and down the Wye, and was in the process of constructing a building on the site which he could use as a base for hunting when it was attacked and destroyed by a force under Caradog ap Gruffydd, King of Gwent.

The excavation revealed that a Norman fortified tower house had existed on the site, probably contemporaneous with the nearby church, and reached by a creek off the Severn.

However, it expanded rapidly later in the 19th century, as housing was built for workers on the Severn Tunnel and with industrial development at nearby Caldicot.

Numerous coins found in the mud show that it was in constant use throughout the Roman period, on the route between Aquae Sulis (Bath) and Venta Silurum (Caerwent).

By the 18th century, a regular ferry service crossed the Severn estuary from Black Rock to New Passage on the Bristol side, carrying passengers, cattle and iron ore.[4] The Black Rock Hotel served travellers and became a popular local entertainment venue; it was later destroyed by fire.

In 1863, the Bristol and South Wales Union Railway built a branch from the main line to Black Rock.

The pier was severely damaged by fire in 1881 and demolished after the Severn Tunnel opened in 1886, but parts can still be seen at low tide.