Lincoln was a strategic town as far back as Roman times. It was situated on the Fosse Way and Ermine Street which were both major Roman roads. Recent excavations have discovered Roman remains on the site where Lincoln Castle now stands.
Lincoln Castle was started in 1068 shortly after the Norman Invasion by the now King William I and during its construction 166 families lost their homes
and were forced to work on the project. It is thought that a wooden defensive structure was built first but after a fire in 1131 it was replaced by the current stone castle. Once completed the building was used to house the King's hostages.
In 1141, the castle was the scene of the first battle of Lincoln between King Stephen and the Empress Maud. Although the siege was unsuccessful, the castle suffered damage and during the renovation work the Lucy Tower was built.
During the First Baron's War in 1217, Lincoln Castle was again besieged; this time by the army of King John. After the hostilities, the castle's defences were improved with the addition of barbicans to the east and west gates.
Although the castle's dungeons had been used to house the monarch's hostages for several centuries, the first purpose built debtors gaol was not erected until 1787. It remained in use until 1878 when the prisoners were moved to a new prison.
In 1826 a new building was erected to the western end of the castle. This formed the Assize courts and today is the home of Lincoln Crown Court.
In 1831, the castle was bought by the city judiciary and in 1884 the castle grounds were opened to the public although the castle itself stood abandoned until the Lincolnshire Archives took over the old prison cells.