Situated close to the M18, south west of Doncaster, Conisbrough is an ancient manor once held by King Harold. However, when William invaded England in 1066, the estate at Conisbrough was given to his son-in-law, William de Warenne. As the first Earl Warenne, it is generally assumed that he would have erected a simple motte and bailey castle but there is no recorded evidence of construction or of life at the castle until the latter part of the 12th century.

Once the 5th Earl Warenne had established himself at Conisbrough, he was responsible for a full scale building programme to provide a fortress and home for the family. Hamelin Plantagenet, the illegitimate half-brother to King Henry II, held the earldom for almost 40 years, and spent a good deal of his time at Conisbrough Castle. During this time, the massive castle keep was built in limestone, to a design that was unique in Britain. Comprising a great circular structure some 90ft (27m) high, with six solid rectangular buttresses evenly spaced around the circumference, this keep was similar only to one found in France - also believed to have been built by Hamelin Plantagenet.

Access to this vast ashlar-faced structure was via an external stairway and wooden bridge at first floor level, and the modern stairs today are located along the line of the original foundations. Internally, the keep was arranged over five levels; a basement, providing a vaulted storage chamber and the castle's well; the entrance level being the main work area; the next two levels comprising the Lord's Hall and Lord's Chamber respectively; and, at the top of the tower, were two observation turrets. Stone curtain walls were also erected about the same time and, subsequently, the domestic buildings in the bailey sprung up.

Conisbrough Castle remained with the Earls of Warenne continuously until 1317 when, after a brief period under the ownership of the Crown, it was returned to the 8th and final Earl, John de Warenne. On his death in 1347, it reverted back to the Crown, passing through various royal descendants. Little more is known of the building history, although work to the buildings in the inner ward was undertaken at the beginning of the 15th century. However, it appears to have fallen into dis-use in Tudor times and a survey from 1537 records detail of various sections of the castle that had become ruinous. Walls, gates and bridges had collapsed, and one floor of the castle keep had fallen in.

Due to the indefensible state of the castle prior to the Civil War, it provided no threat to Cromwell and, as a consequence, escaped being completely destroyed - as was the inevitable fate of many castles during that period. Fortunately for today's visitors, it means they can enjoy exploring a medieval castle that remains largely intact. Although only fragments of many of the domestic buildings can be seen, the foundations remain, and there are many fine features surviving in the keep - notably a grand fireplace and a lovely private chapel. In 1995 the Ivanhoe Trust were responsible for restoring the internal floors of the great tower, and putting on a new roof.

The link with the Ivanhoe Trust comes from Sir Walter Scott's famous novel 'Ivanhoe' where he makes reference to Conisbrough Castle. It is also known that this was one of his favourite castles in England.