Longford Castle is located on the banks of the River Avon south of Salisbury, Wiltshire.

In 1573 Thomas Gorges, of Langford acquired the manor (at the time written "Langford"), which was originally owned by the Cervingtons. Prior to this the existing mansion house had been damaged by fire. In c 1576 Thomas Gorges married Helena Snakenborg, the Swedish born dowager Marchioness of Northampton and Lady-in-waiting to Queen Elizabeth. They rebuilt the Longford property as a triangular Swedish pattern castle on the banks of the River Avon. Unfortunately the building work became very expensive due to problems with the subsoil. Sir Thomas Gorges, who was now governor of Hurst Castle, persuaded his wife to beg of the Queen a shipwreck he knew from the defeated Spanish Armada. The gift was granted and the gold and silver retrieved from the shipwreck funded the completion of the castle under the final supervision of John Thorpe in 1591. The family lived in the castle for several years before its final completion.

The main building had several floors and was triangular with a round tower in each corner; the three towers representing the Father, the Son and the Holy Ghost. There was a chapel, kitchen department, several boudoirs and sitting rooms, as well as bedrooms. Fresh cold water was pumped to various floors and there were water closets operating with rainwater. A park, fruit garden and kitchen garden were attached.

In 1717 Longford Castle became the Bouverie home, purchased by Sir Edward Des Bouverie from the Coleraines. It is said that Sir Edward saw and fell in love with the castle in the valley as he rode past, having enough money in his saddle bags to effect the purchase there and then. Subsequent generations of the family beautified the interior of the castle and surrounding park.

However, Jacob, 2nd Earl of Radnor (1749-1828), employed James Wyatt to change Longford from a reasonably modest chateau into a hexagonal palace "to the despair of future generations" . He destroyed one of the Elizabethan towers and replaced it with a larger one of his own design, added two more towers and linked each to each other. The palace concept was not finished. It was Jacob, 4th Earl of Radnor (1815-1889), who oversaw the last significant changes to the castle architecture, undertaken by Anthony Salvin. These included the formation of a second courtyard, the doming over of the central courtyard and the addition of a square tower that can be seen in the aerial photograph.

Longford has a very fine collection of paintings including examples of the work of the following masters: Holbein (portrait of Erasmus), Velasquez (portrait of a Moorish slave), Quentin Matsys (portrait of Aegidius), Rubens , D. Teniers, Frans Hals, Van Dyck, and Claude. In addition there are a large number of family portraits, many of which are by Reynolds and Gainsborough. The 'Imperial Steel Chair' in the long gallery is a most interesting curiosity, and a marvellous specimen of elaborate and intricate metalwork.

It was bought by the second Earl of Radnor towards the close of the 18th cent. from a Swedish gentleman, and was part of the loot secured at the sacking of Prague. It was made by Thomas Ruker in 1574, and presented by the city of Augsburg to the Emperor Rudolph II. It is divided into some 130 compartments, in each of which a group of figures, carved in relief, sets forth some notable event in the history of Rome and of the Holy Roman Empire.

Longford Castle is currently the seat of William Pleydell-Bouverie, 9th Earl of Radnor, and is not open to the public.