The Coldharbour Gate was a fortification of the Tower of London, inside the current inner courtyard. It divided the space of this courtyard into two zones, following a broken line running from the southwest corner of the white tower and extending the south wall of this tower about fifteen meters, then bifting at right angles to the south to join the bloody tower.
This courtyard was the best protected place in the Tower of London after the White Tower. There were the apartments of the Queen and the King, for example. The Coldharbour Gate is now in a state of ruin, the traces of it are still visible today. It was built a little after 1230 during the wave of fortifications requested by Henry III to protect the royal palace. To be more precise the Coldharbour gate was on the east-west part of this rampart, it was a stocky building made up of 2 joined round towers, like Byward Towers. She had battlements, just like the rampart which pursued her to the bloody tower. The tower served as a prison, but she was not so sure as Alice Tankerville, accused of piracy, managed to escape (thanks, of course, for outside help). This episode took place in 1530.
This tower and its rampart were demolished in the XVIIth century and remained more or less in the state of ruin on the spot. A bomb hit the Tower of London during the Second World War and demolished it. Work to restore the rampart took place at a later date, which explains why today we can still see a good end: it is the wall of the old enclosure.
The map of the tower of London with the list of the buildings