Excavations were carried out in 1977-1978 close to the main gate of the Bendictine Priory and just behind the Norman staircase. The Roman levels were insubstantial and only an incomplete sequence was examined. A Roman courtyard flanked by beamslots dating from the early 2nd century was found. This was sealed by demolition debris of the 4th century. The most important structural remains that were found date from the mid 12th century and comprised the east wall of the vaulted undercroft of the 'Aula Nova' and the monastic drain which led from the necessarium on the south side of the Green Court to the northern city ditch. Underlying the undercroft were found the remains of late Saxon and early Norman houses and pits. Parellel to the drain on its east side was a large flint wall which is thought to be the early Priory boundary wall. The Aula Nova was used as part of King's School from 1573 and was later partly demolished in 1859 leaving only the vaulted undercroft.