Oxford ⁱ/ˈɒksfəd/ is a city in central southern England, the home of the University of Oxford. The city is the county town of Oxfordshire, and forms a district within the county. It has a population of just under 165,000, of whom 153,900 live within the district boundary. It lies about 50 miles (80 km) north-west of London. The rivers Cherwell and Thames (also sometimes known as the Isis locally) run through Oxford and meet south of the city centre.

Oxford has a diverse economic base. Its industries include motor manufacturing, education, publishing and a large number of information technology and science-based businesses.

Buildings in Oxford demonstrate an example of every English architectural period since the arrival of the Saxons, including the iconic, mid-18th century Radcliffe Camera. Oxford is known as the "city of dreaming spires", a term coined by poet Matthew Arnold in reference to the harmonious architecture of Oxford's university buildings. The University of Oxford is the oldest university in the English-speaking world.

Oxford Castle is a large, partly ruined Norman medieval castle situated on the west edge of Oxford in Oxfordshire, England. The original moated, wooden motte and bailey castle was replaced with stone in the 11th century and played an important role in the conflict of the Anarchy. In the 14th century the military value of the castle diminished and the site became used primarily for county administration and for detaining prisoners. Most of the castle was destroyed during the English Civil War and by the 18th century the remaining buildings were used as Oxford's local prison. A new prison complex was built on the site from 1785 onwards and expanded in 1876; this ultimately became HM Prison Oxford. The prison closed in 1996 and was redeveloped as a hotel. Today the medieval remains of the castle, including the motte and St George's Tower, are classed as a Grade I listed building and as a Scheduled Monument.

According to the Abingdon Chronicle, Oxford Castle was built by the Norman baron, Robert D'Oyly the senior from 1071-3. D'Oyly had arrived in England with William I during the Norman Conquest of England in 1066 and was granted extensive lands in Oxfordshire. Oxford had been stormed during the invasion with considerable damage, and William instructed D'Oyly to build a castle to dominate the town. In due course D'Oyly became the pre-eminent landowner in Oxfordshire and was confirmed with a hereditary royal constableship for Oxford Castle. Oxford Castle was not amongst the 48 mentioned in the Domesday Book of 1086, however not every castle in existence at the time was recorded in the survey.