Carlisle Castle is located on the western end of Hadrian’s Wall at an old border between Scotland and England. Currently a Norman Castle dating to the 12th and 13th centuries, Carlisle was a palace and seat of the British Kingdom of Rheged until it was conquered by William Rufus in 1092.

For hundreds of years, even before the arrival of the Roman legions, a British kingdom was centered on Carlisle. Once the Romans conquered Britian, they made where the castle stands today the nucleus of the fort of Luguvalium, which by the middle of the second century was one of the most important military bases in Roman Britain. The British returned after they left and then in turn were conquered by the Normans. Carlisle was besieged both by Robert the Bruce in the Scottish wars for independence and during the War of the Roses. Throughout later centuries, it was often a prison–for border raiders known as ‘rievers’, for Mary Queen of Scots, and for Jacobites, men who supported Bonny Prince Charlie in the 18th century.

The keep was begun by Henry I, augmented by King David of Scotland in the mid-12th century, and then improved again by Henry II and King John. Since then, it has been remodeled many times, depending on the needs of the current century. Today, much of the outer bailey is taken up with extensive barracks and military buildings dating to the 19th and 20th centuries.

In the After Cilmeri series, David is imprisoned in Carlisle at the beginning of Prince of Time, before escaping and time traveling to the 21st century, and it is the setting for the 14th Gareth & Gwen Medieval Mystery, The Faithless Fool.