Geograph - photograph every grid square

The magnificent Norman castle at Chepstow was begun in about 1067 - notably soon after the Norman victory at Hastings. The original owner was William FitzOsbern, though undoubtedly under instruction from William the Conqueror to create a defensive bulwark at this strategic position near the confluence of the Wye with the Severn.
Later important owners included the Marshals, Earls of Pembroke - William, 1st Earl (1147-1219) and his sons, William (2nd Earl), Richard (3rd Earl), Gilbert (4th Earl) and Walter (5th Earl) - up to 1245. This family extended the castle and raised the height of the Great Tower.
In 1270 the castle was inherited by the influential Roger Bigod, 5th Earl of Norfolk, a contemporary of Edward I, who had a variable, occasionally friendly, occasionally stormy relationship with the king. Roger extended the castle further adding a suite of rooms to perhaps accommodate the king should he visit.
The castle had several later owners that modified it in numerous ways, until finally it was partially dismantled from about 1685 and it gradually became the romantic ruin that it is today.
There are plenty of rooms and ruins to explore at this castle and it is well worth a visit. It is owned and cared for by CADW - website here Link

Chepstow/Cas-Gwent is a town in Monmouthshire. It has a castle called Chepstow Castle.

Severn Crossing is a term used to refer to the two motorway crossings over the River Severn estuary between England and Wales. The two crossings are:

The Severn Bridge (Welsh: Pont Hafren)
The Second Severn Crossing (Welsh: Ail Groesfan Hafren)

The first motorway suspension bridge was inaugurated on 8 September 1966, and the newer cable-stayed bridge, a few miles to the south, was inaugurated on 5 June 1996. The Second Severn Crossing marks the upper limit of the Severn Estuary. From 1966 to 1996, the bridge carried the M4 motorway. On completion of the Second Severn crossing the motorway from Aust on the English side to Chepstow was renamed the M48.

The two Severn crossings are regarded as the main crossing points from England into South Wales. Prior to 1966 road traffic between the southern counties of Wales and the southern counties of England either had to travel via Gloucester or take the Aust Ferry, which ran roughly along the line of the Severn Bridge, from Old Passage near Aust to Beachley. The ferry ramps at Old Passage and Beachley are still visible.

Tolls are collected on both crossings from vehicles travelling in a westward direction only. As of January 2012, the toll for small vehicles is £6.20. The Old Severn Bridge is Grade I listed.