Quince Hill, also known as Quints or Old Warden Castle, is a probable 11th-century castle in the village of Old Warden in Bedfordshire.
The castle was probably built by either William Spech, or his son Walter Espec, in the years after the Norman Conquest of 1066. The family held the barony of Warden, which included a manor at Old Warden.
The castle was located on high ground, overlooking the village, and took the form of a “ring motte”, with a large motte at its centre, approximately 150 by 100 m across. The castle was surrounded by an earth bank at least 2.5 m high and protective ditch up to 20 m across and 10 m deep. The castle would have been entered from the north-west, and the motte would have probably supported a timber keep, with possibly some smaller buildings located between the motte and the edges of the defences. There may have been an outer bailey to the south-east of the site towards the village, approximately 100 by 50 m, containing further service buildings.
In 1153, Walter Espec died and his sisters divided his lands between them. The castle may have fallen out of use around this time. Today, only the earthworks on the north-west side of the site still survive, the rest having been destroyed by farming in the 20th century. The remaining earthworks are protected under UK law as a Scheduled Monument.