Thornton Abbey is located close to South End, near Immingham in North Lincolnshire. It was founded as a priory in 1139 by William le Gros, the Earl of Yorkshire, and raised to the status of Abbey in 1148 and eventually a mitred abbey in 1518. It was a house for Augustinian or black canons. These priests lived a communal life under the Rule of St Augustine but also undertook pastoral duties outside of the Abbey.

The enormous and ornate fortified gatehouse of Thornton Abbey is the largest and among the finest of all English monastic gatehouses. An early example of brick building in England, it proclaimed the wool trade-based prosperity of one of the wealthiest English Augustinian monasteries, for centuries a focus of spiritual and economic influence. Begun in the 1360s, the gatehouse was enlarged and fortified with battlements after the Peasants' Revolt of 1381, presumably as insurance against further trouble. Between the four tall turrets above the central vaulted archway, the facade is covered with canopies and niches that once held statues of saints but the crenellated parapets were adorned with stone sculptures of men hurling stones and firing weapons. The upper floors of the gatehouse were thought to have been occupied by the abbots of Thornton Abbey, and several fireplaces and garderobes can be seen throughout the building. Standing some twenty one metres or sixty nine feet high and resembling a castle keep-gatehouse, it may have protected the abbey's treasures, abbey courtroom and administration.

Within the grounds stand the ruins of the monastic buildings, notably the elegantly decorated octagonal chapter house of 1282-1308. These buildings were plundered for stone to build a 'most stately' Jacobean manor house which,mysteriously, 'fell quite down to the bare ground without any visible cause' Abraham de la Pryme. The remains of its formal gardens have recently been rediscovered.

The church was built in two prinicipal stages. In 1261 plans were drawn up for a completely new building including a nave with only one aisle to the left. Work focussed on the liturgically important choir, however which was completed in around 1315. Attention then turned to the nave, the design of which was now altered to incorporate two aisles. Work to the nave progressed steadily through the 14th century under the direction of Stephen the mason. In 1391 a timber vault was built over the interior by the master carpenter William of Riping. It was paved and painted two years later.

The magnificent gatehouse astonishingly survived, and has now been restored to its former glory in an ambitious conservation project. Extensive repairs to the crumbling masonry have been carried out, and a spectacular new exterior oak staircase gives visitors access to the building's atmospheric interior. The gatehouse is open daily, and includes new features revealed following restoration work. A new exhibition offers greater insight into the abbey's history from its foundation to the present day, including its career as the focus of huge Victorian Temperance rallies.