Caldicot Castle was originally built as a motte-and-bailey castle shortly after the Norman Conquest in the late 11th or early 12th Century. At that time, it was strategically important for controlling travel along the River Nedern.

The stone castle is believed to date to the early 12th Century with the keep and curtain walls being constructed by Humphrey de Bohun, Earl of Hereford. The gatehouse and the Woodstock Tower were added by Thomas Woodstock, Duke of Gloucester around 1381AD. Following Thomas's death in 1391AD, the castle reverted to the crown.

Caldicot Castle was eventually granted into the stewardship of the Herbert family during the 15th Century, but it was slighted during the English Civil War sometime around 1640AD. From this time onwards, the castle fell into decline and ruin.

In 1855AD the antiquarian JR Cobb purchased Caldicot Castle and restored it in a sympathetic fashion true to its mediaeval past.

In the aftermath of the second world war, housing was in short supply and Joseph's grandson converted rooms in the tower and part of the gatehouse to be rented out as flats to local families. By 1963AD the need for housing had eased, and the castle was purchased by Chepstow Rural District Council who opened it to the public.

Today, the castle remains free to enter to members of the public. Arguably one of Wales's best kept secrets, the fortress sits in extensive grounds offering an oasis of tranquillity a short distance from the River Severn and the M4 crossing. On quiet days, it's a pleasure to stroll around. On busier days, the accessibility of the site and the many events put on to entertain families make for a much busier experience.