Traitor's (or Traitors') Gate was a watergate – originally simply called the Water Gate – beneath St Thomas's Tower at the Tower of London. The gate was built in the late 1270s on the orders of Edward I to provide a convenient means by which he could arrive by barge.

When was the traitors gate used?

The name Traitors' Gate has been used since before 1543, when that name is used on Anton van den Wyngaerde's panorama of London. Prisoners were brought by barge along the Thames, passing under London Bridge, where the heads of recently executed prisoners were displayed on spikes.

Why is it called Traitor's Gate?

Over the following centuries, as the Tower of London became increasingly a prison for state enemies accused of treason, it acquired its current name of "Traitors Gate" because of the number of prisoners accused of treason which are passed through.