St Anne's Tunnel East Portal (MLN111641)

St Anne's Tunnel East Portal is a 19th-century structure made of Pennant stone. The stone is squared and coursed on the portal face, soffit, and attached retaining wall, with ashlar dressings including voussoirs, copings, crenulations, machicolations, quoins, and side tower faces. Some areas have been patched with engineering brick.

The portal features an asymmetric design with a round arch that spans 30 feet (9 meters). The arch is made of plain double voussoirs, set back and chamfered, with some repairs in engineering brick that mimic the original style. Below the arch, there are plain spandrels topped by a flat coping. On the north side, there is a square tower with two arrow-loops, topped with double-step corbelled machicolations that support a projecting embattled parapet with sloping copings. The south side of the portal meets a battered, rubble-faced retaining wall.

Additional detached sections of retaining wall and buttresses can be found against the face of the cutting towards Bath. The portal is located at the western end of a short stretch of railway that runs along a shelf between a steep hillside and the River Avon, which was diverted by Isambard Kingdom Brunel. At the opposite end of this stretch is the West Portal of Fox's Wood Tunnel, which is also listed as Grade II*.