When archaeologists moved in ahead of commercial development in 1981, they found not only the fourteenth and fifteenth-century town walls and the foundations of the West Watergate, but the remains of a seventeenth-century quay wall that had once contained a narrow water-filled channel running from the Abbey River up to the Watergate's northern tower. The whole arrangement had been quietly buried under the city's later street level, with nineteenth-century basements and building foundations built directly on top of it.

The area immediately outside the town walls, to the west of the West Watergate, was marshy and largely empty for much of the medieval and early modern period. A sketch by Phillips in 1685 shows only a few scattered cabins in the vicinity. It was not until 1717 that Messrs Vincent, Wight and Holland took a lease from the Corporation and built a quay there, known initially as Mardyke. The town walls themselves came down in the late eighteenth century, and Charlotte's Quay as it exists now was constructed around that same period, supported by a complex series of brick relieving arches, the kind of broad, load-distributing brick structures often used to stabilise ground above vaulted or unstable foundations. What the 1981 excavations revealed beneath all of this was a seventeenth-century quay wall 32.5 metres long, nearly a metre wide, and up to 3.2 metres high, built in limestone ashlar with a rubble core, and showing two clear phases of construction. The lower courses are carefully laid, hammer-dressed limestone blocks; the upper portion, added or refaced later, uses noticeably smaller stones with less regular coursing. A small rectangular drainage opening near the base, fitted with a flattened arch, had at some point been blocked up with brick from behind.

The site itself is not a visitor attraction in any conventional sense; the excavated remains are not on public display, and the quay wall now lies below street level and within the footprint of later development. What the area does offer is a useful exercise in reading a city's surface against its buried layers. The maps held up against the excavation findings tell an interesting story of disagreement: Speed's map implied a water-filled moat around Irish Town that left no physical trace in the ground, while a 1691 map depicting an elaborate double rampart and moat system appears to have recorded planned or desired fortifications during the Williamite sieges rather than anything that was actually built. The southern end of the quay wall was broken through at some point in the modern era, meaning the precise arrangement of the landing area beside the Watergate remains unresolved.