It is open to the public most days of the week and possible to walk around the walls from which there are views of the castle complex, cathedral, the city, and surrounding countryside.

[2] After William the Conqueror defeated Harold Godwinson and the English at the Battle of Hastings on 14 October 1066, he continued to face resistance to his rule in the north of England.

[3] When William reached Lincoln (one of the country's major settlements), he found a Viking commercial and trading centre with a population of 6,000 to 8,000.

The remains of the old Roman walled fortress of Lindum Colonia (source of the name 'Lincoln'), located 60 metres (200 ft) above the countryside to the south and west, proved an ideal strategic position to construct a new castle.

[7] The castle was the focus of attention during the First Battle of Lincoln on 2 February 1141, during the struggle between King Stephen and Empress Matilda over who should be monarch in England.

[9][11] In 1375, one Agatha Lovel – "notoriously suspect" in the murder of her master, Sir William de Cantilupe[12] – escaped justice by bribing her Lincoln Castle gaolers, where she had been imprisoned awaiting trial.

The bailiffs, Thomas Thornhaugh and John Bate, were later arrested and tried for allowing Agatha to escape justice, but were either pardoned or acquitted.

At Lincoln, the gaol was built in 1787 and extended in 1847 – the 1787 Governor's House and the 1847 Prison are now Grade II* heritage listed buildings.

[18] Parts of the prison are open as a museum, including the 19th-century chapel which is claimed to be the only one remaining in the world designed for the separate system (each seat enclosed).

Work involved creating a new exhibition centre in which to display Lincoln's copy of Magna Carta, building visitor facilities, and opening sections of the prison within the castle to the public.

[22] The grounds also contain remains of Lincoln's Eleanor cross,[23] an oriel window moved from Sutton Hall and incorporated into the main gate, and the bust of George III from the Dunston Pillar.