Newark Castle, in Newark-on-Trent in the English county of Nottinghamshire, was founded in the mid 12th century by Alexander, Bishop of Lincoln. Originally a timber castle, it was rebuilt in stone towards the end of the century.

Newark-on-Trent is a market town, an inland port and a civil parish in the Newark and Sherwood district of Nottinghamshire, England. The town and parish contain over 360 listed buildings that are recorded in the National Heritage List for England. Of these, four are listed at Grade I, the highest of the three grades, eleven are at Grade II*, the middle grade, and the others are at Grade II, the lowest grade. The history of the town is reflected in its buildings, from the remains of the 12th-century castle, through a number of surviving timber framed buildings, to the many Georgian buildings of the 18th century. In the 15th and 16th centuries, wool merchants thrived in the town, followed by drapers, mercers and cloth merchants. By the 18th century, the town was an important staging post on the Great North Road. The town is on the River Trent, which was partly canalised in the late 18th century, encouraging industries including malting, brewing and engineering.