Wessex archaeology was invited to attend during investigatory works adjacent the Rochester Castle curtain wall to ascertain the location of a purportedly bricked up Sally-port, to aid in the repair of below ground utilities along Rochester Esplanade. The works at Rochester Esplanade revealed the buried remains of the northwest bastion wall, internal shaft and water-gate, likely built between 1378 and 1397 as part of the final major phase of construction at Rochester Castle. The work also revealed a revetment wall and access steps which formed a 'viewing chamber' and may have been constructed around 1856 during works to create the Esplanade as a way to protect the buried archaeological remains. The last record of the water-gate was made in 1956 during consolidation works at Rochester castle. The access steps have been buried beneath Rochester Esplanade since.
Archaeology Wessex (Thu,) studied this question.